The Senate election map is so favorable for Republicans that they should be significantly adding to their majority instead of laboring to defend it.

But with Democrats emboldened by opposition to President Donald Trump, and no Democratic senators retiring this year, the Nov. 6 election may again result in a chamber about evenly divided between the two parties.

Democrats, who control 49 seats in the 100-member chamber, even have an outside shot at winning a majority, despite having to defend 26 Senate seats compared to merely nine for the Republicans.

Of the five Democratic senators defending seats in states Donald Trump won overwhelmingly in 2016, Heidi Heitkamp (N.D.), Claire McCaskill (Mo.) and Joe Donnelly (Ind.) probably are in tougher re-election campaigns than Joe Manchin (W.Va.) and Jon Tester (Mont.)

Democrats are defending seats in five other states that were more modestly pro-Trump in 2016. Among those, Florida has a highly competitive and expensive contest between Sen. Bill Nelson (D) and Gov. Rick Scott (R). Democratic incumbents in Wisconsin, Michigan, Ohio, and Pennsylvania are more politically secure if not completely safe.

Since the beginning of the year, the top targets for Democrats have been the Arizona seat of Jeff Flake (R), who’s retiring, and the Nevada seat that Dean Heller (R) is defending. Polls show both races close.

Democrats are making a major play for an open Republican seat in Tennessee, which Trump won by more than 25 percentage points. Phil Bredesen (D), a well-regarded governor from 2003 to 2011, might be the only Tennessee Democrat who would win here. He’s up against Rep. Marsha Blackburn (R).

In Texas, which has voted Republican in every statewide election since 1994, Rep. Beto O’Rourke (D) is giving Sen. Ted Cruz (R) a run for his money. Polls show Cruz with a small but steady advantage.

And don’t overlook a special election in Mississippi, which would go to a runoff Nov. 27 if no one wins a majority of the vote in an all-party, single-ballot race. Sen. Cindy Hyde-Smith (R) is favored to keep her seat, though a Mississippi runoff could determine Senate control if no party has secured control of 51 seats when the smoke clears Nov. 6.