Several prospective 2016 major party presidential candidates will be making their plans known in the weeks ahead. Here's a summary of those, as well as a list of those that have declared and those that have formed exploratory committees (or similar) but have not made any further announcements regarding their 2016 candidacy. 

May 27: Former Pennsylvania Senator Rick Santorum (R) is likely to run

May 28: Former New York Governor George Pataki (R) may or may not run

May 30: Former Maryland Governor Martin O'Malley (D) is expected to run

June 1: South Carolina Senator Lindsey Graham (R) is expected to run

June 4: Former Texas Governor Rick Perry (R) is expected to run 

Declared Candidates

Democrat: Hillary Clinton, Bernie Sanders

Republican: Ben Carson, Ted Cruz, Carly Fiorina, Mike Huckabee, Rand Paul, Marco Rubio 

Exploratory Committee

Democrat: Lincoln Chafee, Jim Webb

Republican: Jeb Bush, Chris Christie, Bobby Jindal, John Kasich, Donald Trump, Scott Walker

Update May 18: Bobby Jindal announces the launch of his exploratory committee

A trio of Republicans not currently holding office will formally announce they are running for president early this week. They will join the three sitting Senators (Ted Cruz, Rand Paul, Marco Rubio) who previously launched their campaigns. While the new entrants start out with longer odds to be the eventual Republican nominee, each brings a set of attributes that can certainly impact the race.

This will be the 2nd presidential run for former Arkansas Governor Mike Huckabee, who previously ran in 2008. That year he won the Iowa Republican caucuses and continued his campaign until March, when it became apparent that Arizona Senator John McCain would be that year's Republican nominee. At the national level, Huckabee performs best in states with a larger evangelical Christian population, putting him in a decent position to impact the early caucus/primary states of Iowa and South Carolina. Huckabee is set to announce on Tuesday.

Former Hewlett-Packard CEO Carly Fiorina joins the race Monday AM. Fiorina is expected to be the only woman in the Republican field and further distinguishes herself from the field with a strong business background. Of the three announcing this week, she is likely to be seen as the most moderate. Fiorina previously ran for Senate in California in 2010, losing to incumbent Barbara Boxer. Fiorina has received minimal support in early polling; it will be interesting to see if that shifts as she becomes more well-known.

Retired neurosurgeon Dr. Ben Carson made his 2016 announcement Sunday night. The only African-American likely to run for the 2016 Republican nomination, Carson became a star in conservative circles after a well-received speech at the 2013 National Prayer Breakfast. Carson has not previously run for political office. Carson has been receiving about 5% support in early polls and will be competing with Huckabee for many of the same voters.

Independent Vermont Senator Bernie Sanders will challenge Hillary Clinton for the 2016 Democratic nomination, Vermont Public Radio reports. Sanders will make his announcement Thursday via a short statement, followed by a kickoff campaign in Vermont in several weeks.

Sanders provides Clinton with a challenge from the left. Former Maryland governor Martin O'Malley is also considering a run as a progressive challenger to Clinton. Sanders has been polling about 5% in recent Democratic nomination surveys.

Barack Obama won Vermont by over 35% in 2012. (As an aside, while deep blue today, Vermont voted Republican in every election from the founding of the modern party in 1854 through 1988, except for 1964).

Two polls late this week, from Quinnipiac and Fox News, arrived at roughly the same conclusions.

• Marco Rubio has edged into the lead in the crowded Republican field
• Hillary Clinton maintains a single-digit lead over her most likely general election opponents
• Clinton has this lead despite most finding her not honest and trustworthy

Quinnipiac found that 54% thought Clinton wasn't honest and trustworthy, while 38% thought she was. Fox News was closer, with 51-45% doubting her. These results were worse than most of her prospective opponents. Despite this, she continues to lead the Republican field. The polls found margins of 2-7%.

Full results, as well as other national and state polls can be found on our 2016 polls page.

Turning to the Republican nomination, Marco Rubio led in both polls, showing 15% support in the Quinnipiac poll, 13% in the Fox News survey. Overall the field remains tightly bunched.

It is possible that some of these poll results are a bit distorted by current news: Rubio's recent 2016 announcement and enhanced scrutiny of Clinton since her official announcement. Time will tell.

Former Hewlett-Packard CEO Carly Fiorina will launch her presidential campaign on May 4, the Wall Street Journal reports. Fiorina will join Senators Ted Cruz, Rand Paul and Marco Rubio who have already declared.  Dr. Ben Carson and former Arkansas governor Mike Huckabee are expected to make known their 2016 plans the same week as Fiorina's announcement.

Fiorina has never held elected office. She was the Republican nominee for California's 2010 Senate race, losing by 10 point to incumbent Democrat Barbara Boxer. Fiorina has not made much of an impact in early Republican nomination polling, averaging about 1%. 

Fourteen Republicans garner at least 2% support for the 2016 nomination, according to the latest poll from CNN-ORC. Hillary Clinton continues to own the Democratic side and maintains double-digit leads in all tested November, 2016 match-ups. 

Republican Primary: Jeb Bush leads Scott Walker 17-12%, with Rand Paul and Marco Rubio just back at 11%. Mike Huckabee is at 9%, with Ted Cruz at 7%. Eight other Republicans saw 2-4% support. For the most part, these numbers are similar to last month's CNN-ORC poll

Democratic Primary: Clinton received 69% share in the survey, her highest number to-date. The poll did not include Elizabeth Warren as a named option with most of her support (10%) in the last CNN-ORC poll going to the front-runner. Former Rhode Island governor Lincoln Chafee was polled for the first time, receiving 1%.

General Election: Clinton crushes the Republican field in each prospective match-up. Rubio performs best, trailing Clinton by 14%. Hard to read too much into the general election numbers at this point, given the awareness advantage Clinton has over a fragmented Republican field.

A new poll from Marquette Law School shows Hillary Clinton well in front of five prospective Republican 2016 opponents, including a 12% lead over that state's governor, Scott Walker. 

Republican Primary: Governor Walker is dominant here, preferred by 40% of Republicans (and those leaning Republican) polled. Rand Paul was second with 10% and Jeb Bush third with 8%

Democratic Primary: Hillary Clinton received 58% of the Democratic (and leaning Democratic) vote, with Elizabeth Warren at 14% and Joe Biden at 12%. 

General Election: Clinton's lead ranges from 8% over Rand Paul to 16% over Ted Cruz. Her lead is 11% over Jeb Bush and 12% over Marco Rubio and Walker. Interestingly, Walker received exactly 40% support in both the primary and general election surveys. The initial NBC 2016 Electoral Map* (from late 2014) shows Wisconsin as a possible battleground state, although this poll and one taken last month don't support that idea. Wisconsin last voted Republican in the 1984 Reagan landslide; Obama won the state by 7% in 2012.

*For those of you visiting from a mobile device, you will now be able to see and use 270toWin interactive maps. We have launched a map that doesn't use Flash for those visiting from smartphones and tablets.

Those of you visiting 270toWin from a tablet or smartphone will now be able to create an interactive electoral map and view the maps and forecasts created by others. This will probably be a bit more useful than the mostly blank screen previously 'visible' on devices unable to display Flash objects in the browser.

Home Page: On a mobile device, you'll see the new map, initially set to the results of the 2012 election. Tap states to create your own forecast. If cookies are enabled, your map should be as you left it when you return to 270toWin

Shared Forecasts: You can view maps created on the Flash version and shared by others. These will be displayed using the new map. For example, the NBC Battleground 2016 map. 

Polling Maps: We've created a series of electoral maps that show how different Republicans are performing against Hillary Clinton, purely based on early polling. These will now be visible on your device.

In the weeks ahead, we'll be upgrading the new map, adding many of the other features of the Flash map. 

If you have any feedback or run into any issues, please add a comment to let us know.

Florida Senator Marco Rubio became the third Republican Senator to join the 2016 presidential race on Monday, joining Kentucky's Rand Paul and Ted Cruz of Texas. Rubio held a call with donors Monday morning to let them know he was running. A public announcement will come this evening at downtown Miami's Freedom Tower.

Rubio has averaged about 7% in recent Republican preference polling putting him in the middle of the pack, trailing his political mentor Jeb Bush who is polling in the mid-teens in a crowded field of prospective nominees. Bush has not yet declared his candidacy for 2016.

There hasn't been a great deal of early polling for a general election match-up between Rubio and Hillary Clinton; that link will let you track the race and also links to an interactive map that looks at polling + 2012 results in unpolled states.

Hillary Clinton will announce her entry into the 2016 presidential race today, Sunday April 12, the New York Times reports. Clinton is expected to begin her campaign with a video message on social media, followed by visits to early primary states in the days ahead.

Clinton has dominated the Democratic field in early polling for the 2016 nomination, usually earning over 60% support and leading her prospective rivals by an average of almost 50% in the last 5 national polls, 270toWin has calculated. 

While Clinton enters the 2016 race as a prohibitive favorite, it is worth noting that she was the presumed front-runner at this same time in 2007, polling about 35-40%, about 10% ahead of a not-yet-well-known Senator from Illinois. On the Republican side, Rudy Giuliani was seeing twice as much support as John McCain.

Looking ahead to November, 2016, there has been some polling on Clinton vs. a number of prospective Republican nominees. We're tracking those with a series of electoral maps*. 

*We are creating a non-Flash version of our interactive electoral maps to provide a much better experience for the growing percentage of 270toWin visitors viewing the site from a mobile device. You should start seeing this map in the next few weeks.