6th Term Democratic Rep. Niki Tsongas (MA-03) has announced she will not seek reelection to the House in 2018. This brings to 21 the number of Representatives that will not seek another term. The updated list, along with the current ratings, courtesy of Sabato's Crystal Ball, can be seen in the table below.

Of the 21 leaving the House, 13 are Republicans (R), eight are Democrats (D). Eight (5R, 3D) are running for governor of their state, while five (3R, 2D) are running for U.S. Senate. One Democrat is running for president in 2020. The remaining seven (5R, 2D) are retiring, or are not currently seeking another office. 15 seats (9R, 6D) are considered safe for the incumbent party, while the other six (4R, 2D) are expected to be at least somewhat competitive.

All 435 House seats will be up for election in 2018. 

The Associated Press is reporting that Republican Rep. Todd Rokita (IN-4) will announce a Senate run on Wednesday morning. Rokita will join fellow Republican Rep. Luke Messer (IN-6) in the race to defeat incumbent Democratic Senator Joe Donnelly. This announcement was not unexpected. As only one of the two congressmen will make it to the general election, they have been feuding in recent weeks. Each has suggested that the other is "unhinged".

Donnelly is among the more vulnerable Democrats in 2018. The race is currently rated toss-up by Larry Sabato's Crystal Ball. An interactive version of that forecast can be found here.

Rokita will be the 20th House member to announce a departure from that body in 2018. Most are running for U.S. Senate or to be Governor of their state. 

A poll of likely Republican primary voters in New Hampshire finds that Ohio Governor John Kasich would beat either President Trump or Vice-President Pence. Kasich saw 52% support to Trump's 40%, while Kasich led Pence 41% to 27%. About 1/3 of those responding were undecided in the case of Kasich vs. Pence.

Beyond the many obvious reasons why a poll 900 days before an election is of limited predictive value, we wanted to highlight the note at the bottom of the poll's report:

"This is only the second time since the New Hampshire Poll began in 1976 that potential challengers of the same party were tested against an incumbent president. The first time was in the September 1978 New Hampshire Poll when Jerry Brown and Edward Kennedy were included in a ballot question with Jimmy Carter. In that poll among likely Democratic primary voters, Kennedy took the lead with 40%, followed by Carter at 25%, Brown at 13%, and with 22% undecided."

As in today's poll, the incumbent president -- then Jimmy Carter -- trailed by double digits.  However, Carter would go on to win the 1980 New Hampshire primary by nearly 10% and would be renominated for a 2nd term. Carter would eventually be defeated in the 1980 presidential election.    

The New York Times is reporting that some high-profile Republicans "have begun what amounts to a shadow campaign for 2020 — as if the current occupant of 1600 Pennsylvania Avenue weren’t involved." Courting of prominent donors, visits to Iowa and appearances at party-affiliated events are among the activities being undertaken. Names mentioned include Vice-President Mike Pence, Senators Tom Cotton of Arkansas and Ben Sasse of Nebraska, Ohio governor John Kasich, and U.N Ambassador Nikki Haley. 

At this point, most are indicating they would only be active in 2020 if President Trump declines to run for a second term. Of course, that could change pending the outcome of the Russia investigation, the results of the 2018 Midterms and the president's popularity. It is worth noting that election year nomination challenges to incumbent presidents have not been particularly successful. At the same time, they are indicative of a split and this usually portends the party's defeat in November.

While no date is set, the 2020 Iowa caucuses are about 900 days away. 

Once a Republican, Jim Justice switched his registration to run for West Virginia governor as a Democrat in 2016. Now he's changing parties again. An announcement is expected Thursday night during a rally with President Trump, who won the state by 42 points last November.

Once the change is made, there will be 34 Republican governors, tying a mark set nearly a century ago.

August 3 Updates:  Republican Diane Black (TN-06) announced she will run for governor of the state in 2018. Additionally, although no formal announcement has been made, it seems highly likely that Republican Lou Barletta (PA-11) will run for U.S. Senate.  Neither of these are yet reflected in the table below.  

We've updated the table of U.S. House members not seeking reelection to their seat in 2018. The list is up to 18, including 11 Republicans and 7 Democrats. 

Over the past couple weeks, there have been three additions. In Indiana, Republican Luke Messer (IN-6) has announced his candidacy for U.S. Senate. Note that he may be joined in that race by his colleague, Republican Todd Rokita (IN-4). In Tennessee, 16-term Republican John Duncan Jr. (TN-2) has announced his retirement. Finally, as reported last week, Democrat John Delaney (MD-6), will be retiring from the House to run for president in 2020.

All three of these seats are currently rated as safe for the incumbent party, although there is some possibility that the Democratic-held seat in Maryland could become more competitive.

The House currently has 240 Republicans and 194 Democrats. Utah's 3rd district is vacant, to be filled by a special election on November 7th. All 435 House seats will be up for election in 2018. 

Democrat John K. Delaney, who represents Maryland's 6th congressional district, has become the first formally declared challenger to a second term for President Trump.  Delaney, who is in his third term, will not run for Congress in 2018 so that he can focus on the presidential bid. Delaney laid out his rationale for running in a Washington Post opinion piece and has launched his campaign website that includes this video:

There are just over 1,190 days until the 2020 presidential election, making Delaney's announcement the earliest one in recent history (probably longer). Delaney is not well-known nationally, so the novelty of going first will garner him some attention.

We've added Delaney as a candidate option (click or tap 'Democrat' above the electoral counter) on the 2020 interactive map.

The chart below shows how individual states have voted in each presidential election since 1900. For each state/year, you can view: 

• The number of electoral votes allocated to the state
• Which party's nominee won the popular vote
• If the state voted with the person that won the presidential election
• If the winner received fewer than the total electoral votes available

For more information, including a larger version, click/tap the chart, or see the state electoral vote history page.

New Mexico Republican Rep. Steve Pearce announced that he will run for governor of that state in 2018. Incumbent Gov. Susana Martinez, also a Republican, cannot run again due to term limits. Pearce's colleague in the House, Democrat Michelle Lujan Grisham had previously announced her entry into the race. A poll from earlier this year gave Martinez just a 43% approval rating. The gubernatorial race is currently rated 'Lean Democratic' by Sabato's Crystal Ball.

14 current members of the House have announced they will not be seeking reelection in 2018. The list includes eight Republicans and six Democrats. Three of the Republicans are retiring, while the other eleven members are running for Governor or U.S. Senator. Five of the 14 seats are expected to have competitive races in 2018.

Two House seats are currently vacant. Democrat Jimmy Gomez (CA-34) is expected to be sworn in on Tuesday. UT-03, previously held by Jason Chaffetz, will be filled via a special election to be held on November 7th. 

First-term Democratic congresswoman Jacky Rosen has formally announced her candidacy for U.S. Senate in 2018. Assuming she secures the nomination, she will take on Republican incumbent Dean Heller, who will be seeking reelection to a 2nd term in the Senate from Nevada. Rosen currently represents that state's 3rd congressional district, which encompasses most of the state south of Las Vegas.

A late June poll from Public Policy Polling showed Rosen and Heller virtually tied, with Rosen ahead 42% to 41%. This will be one of the most watched races of 2018 as it is one of the few realistic opportunities for a Democratic pick-up on a difficult map. Of the 34 seats to be contested in 2018*, 25 of them are already held by Democrats**. Of the nine Republican-held seats, Nevada is the only one in a state not won by Donald Trump in 2016. Aside from Nevada, of the ten races currently seen as most competitive for next year (tan on map below), only Arizona is currently in Republican hands.

To win control of the Senate, Democrats need a net gain of three seats. To do that, they would need to defend all 25 of their seats, win the two competitive Republican-held seats (Nevada & Arizona), and find one other pick-up in a deep red state. Click or tap the map above to create and share your own 2018 Senate forecast. 

*   Includes Alabama special election to be held on December 12, 2017

** Including two independents (Bernie Sanders, Angus King) that caucus with the Democratic Party