Donald Trump may have inadvertently just given Senate Democrats their second break in two days, in a campaign cycle where they badly need as many as they can get.

The break: The president-elect has chosen Rep. Ryan Zinke (R-Mont.) to serve as secretary of the interior.

Although most of the nation has never heard of the guy, Senate Democrats know the one-term Montana congressman well: He was widely expected to challenge one of their most vulnerable members in 2018, Sen. Jon Tester. And he had a decent chance of winning — Trump won the state by more than 20 points. Plus, Montana has only one congressional seat, which means Zinke has already successfully campaigned statewide twice.

Recognizing the threat he posed, Senate Democrats tried to knock Zinke this November by funding a strong Democratic challenger. But Zinke ended up beating Denise Juneau by 16 points.

If Zinke accepts the job and is confirmed by the Senate, Trump will have done what Senate Democrats could not: taken one of their biggest competitors out of the picture. It's not clear what other Republican could launch a credible statewide campaign to unseat a senator. (Montana's Democratic governor, Steve Bullock, just won reelection.) If the Senate confirms Zinke, Bullock will appoint his replacement from a list of three nominees selected by Republicans, but just a few months later a special election would occur.

This lucky break for Senate Democrats comes just a day after another one: Sen Joe Manchin III (D-W.Va.) said he'll stay in the Senate.

Any other scenario involving Manchin — him accepting a job in the Trump administration or retiring — would have been very, very bad for Senate Democrats. Both those were possibilities, and yet he decided to stick it out for a potentially tough reelection battle. Which is better than no shot at all.

“Had Manchin abandoned his seat,” Chris Cillizza wrote on The Fix on Tuesday, “there was a roughly zero chance Democrats would have held it in 2018.”

But for every break Senate Democrats have over the next two years, they're going to need about a gazillion more if they want to retake the Senate majority they lost in 2014. Democrats are facing one of the unfriendliest maps for any party in nearly half a century.

The way the numbers stand, they'll need to pick up three seats to retake the majority. (The current breakdown now is 52 Republicans to 48 Democrats.) And just like Republicans were disproportionately on defense in November, Senate Democrats will have to defend 25 seats next time around, compared to Republicans' eight.

What's more, Manchin and Tester are just two of 10 Senate Democrats fighting for reelection in states that voted for Trump, in some cases overwhelmingly. Trump's margins of victory over Hillary Clinton in five key states where Senate Democrats are up for reelection are among his most impressive wins anywhere:

  • In West Virginia, Trump beat Clinton by 42 points!
  • In North Dakota (where Democratic Sen. Heidi Heitkamp could deliver a big blow to her party by doing what Manchin chose not to do by working in a Trump administration), Trump won by 36 points.
  • In Indiana (where Sen. Joe Donnelly is up for reelection), Trump won by 19 points.
  • In Missouri (where Sen. Claire McCaskill is up for reelection after winning six years ago against a flawed opponent), Trump won by 19 points.
  • And of course, there's Montana, where it looks as though Tester will run for reelection against a TBD opponent. Trump won that state by 20.5 points.

There's a potentially powerful political wind at Senate Democrats' backs, though. The party out of power typically picks up seats in Congress in midterms. Democrats consistently lost seats in Congress in the midterms after President Obama was elected, and Democrats have every reason to expect the reverse to be true.

Then again, their map is so daunting, political precedent may not matter. As Kyle Kondik and Geoffrey Skelley, nonpartisan political handicappers at the University of Virginia, wrote recently:

Thus the 2018 midterm cycle features a clash of two patterns in American politics. On the one hand, the president’s party almost always suffers to some extent in midterm elections, though more consistently in the more-nationalized elections for the U.S. House than in the more-parochial elections for the U.S. Senate.
On the other hand, in this polarized era of American politics, the fact that Democrats are defending seats in some very Republican states suggests that the GOP should be in a good position to pick up seats despite the midterm environment.

In short: Senate Democrats are going to need every lucky break they can get. Two down; an untold number more needed.