Despite near-instant media prognostications the GOP could lose its slim majority in the U.S. Senate come the 2018 midterm elections, it is actually Democrats who face an uphill climb.

An unfavorable map in 2018 could all but guarantee Democrats remain shut out from government for at least four years. In 2018, Democrats will have to defend at least six highly endangered incumbents in red to red-leaning states.

The incoming Trump administration can use that advantage to pressure endangered Democrats to support their agenda.

The high number of likely endangered Democrats in 2018 also will give the Trump administration a powerful tool. The administration can put enormous pressure on these Democrats to back certain agenda items, like new approval of the Keystone XL pipeline and the repeal of Obamacare, lest they face angry conservative voters at home.

There are 34 seats to be decided in the 2018 midterms. Twenty-six are held by Democrats — and one by Bernie Sanders, the socialist independent from Vermont.

Republicans have to defend just eight. Only two of those races will occur in states that had relatively close margins for Trump: Nevada, which Trump lost, and Arizona, which Trump won. The Republicans in those states, Sen. Jeff Flake of Arizona and Sen. Dean Heller of Nevada, will likely be targeted.

Democrats are up for re-election in 10 states won by Trump.

If those Democrats obstruct and block the Trump agenda, they could suffer strong challenges in the 2018 midterm elections.

Usually, the party out of the White House does well in the first midterm elections. The Republicans won historic margins in 1994 and 2010.

But in 2002, the Democrats lost seats in the House and Senate after fighting with President George W. Bush on issues from taxes to national security. Most damaging for the Democrats that year: They lost their Senate majority.

The Republicans lost their own midterm battle in 1998. It was the final midterm election of Bill Clinton’s presidency. After being seen as intransigent, the GOP lost five seats in the House of Representatives and gained none in the Senate.

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With so many seats for the Democrats to defend in 2018, however, the Republicans have a natural advantage. In the meantime, the incoming Trump administration can use that advantage to pressure endangered Democrats to support their agenda.

Here are six Democrats who will be most likely to feel the heat.

Indiana
Sen. Joe Donnelly of Indiana won in 2012 thanks to two things: One, voters were still upset that six-term Sen. Dick Lugar, a Republican, had been beaten in the Republican primary. Two, the GOP candidate, then-Treasurer Dick Mourdock, made a gaffe at the final debate.

Donnelly won, but he has been running to the center ever since.

Montana
Democrat Sen. Jon Tester is a likely GOP target — because he always is.

He won in 2006 mostly because of a large Democratic wave then. And he sits in a conservative but independent state.

His liberal leanings have not been a liability, but he made himself vulnerable by voting for Obamacare. This seat will be a top target.

West Virginia
Sen. Joe Manchin is highly vulnerable — and he knows it. There have been rumors he could switch parties due to the conservatism of the constituency he represents.

The former governor won election in 2012 in a conservative state. He is a well-liked figure in West Virginia, but voters in his state have flocked to the Republican Party due to the Democrats’ extreme positions on coal.

West Virginia was also the site of Trump’s best performance on the list of states where Democrats must fight in 2018. He got 72 percent of the vote there.

Missouri
Sen. Claire McCaskill could be a top target. The liberal Democrat won an upset victory during the Democratic wave in 2006. But when she ran for re-election in 2012, she realized her liberal views could be a poor fit for the Midwestern state.

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That’s when McCaskill manipulated her desired GOP opponent, Todd Akin, into running primary ads she knew would help him. This is a violation of campaign coordination laws; she admitted it in her own book.

Akin won, then made a terrible gaffe on abortion that delivered the general election to McCaskill. Missouri is a conservative heartland state that gave Trump 60 percent of the vote.

North Dakota
Sen. Heidi Heitkamp won her seat in a 2012 upset. She could be a tough opponent as she served as attorney general in the conservative Great Plains state. She is a known quantity.

But she is also a Democrat in a state that Trump won with 70 percent of the vote. Only West Virginia gave Trump a larger share.

She is likely to listen to Trump on a lot of issues. Otherwise, she is a target.

Florida
Sen. Bill Nelson isn’t particularly vulnerable. He won re-election easily in 2012.

But Florida has grown more friendly toward Republicans in recent years, and he could draw a strong opponent like Gov. Rick Scott in 2018.

Scott’s approval ratings are rising, and Trump won the Sunshine State in both the GOP primary and the general election.