Democratic Sen. Tom Udall is not seeking re-election in 2020, making him the first Democratic senator to retire since 2016. For Democrats, Udall’s exit means they’ll have to defend what likely would have been a safe seat. Republicans have few targets on the 2020 Senate map, and New Mexico could mark one of their few take-over opportunities. Still it won’t be easy for them to win — New Mexico is not quite solidly blue, but it’s also not quite purple either. It’s the type of state a Republican could win, but they would need multiple things to go their way.

First of all, Democrats are favored to hold the seat. Election handicappers at the Cook Political Report and Sabato’s Crystal Ball still view the New Mexico contest as “Likely Democratic” while Inside Elections gave it a “Solid Democratic” rating. The Land of Enchantment is 7 percentage points more Democratic than the nation as a whole, making it the 14th-most Democratic-leaning state in the country.

New Mexico is blue, but it could prove competitive in 2020 Senators up for re-election in 2020 and their states’ partisan leans* Incumbent NAME Party State Partisan Lean Ed Markey D Massachusetts D+29.4 Jack Reed D Rhode Island D+25.7 Chris Coons D Delaware D+13.6 Cory Booker D New Jersey D+13.3 Dick Durbin D Illinois D+13.0 Jeff Merkley D Oregon D+8.7 — D New Mexico D+7.2 Susan Collins R Maine D+4.9 Tina Smith D Minnesota D+2.1 Cory Gardner R Colorado D+1.5 Gary Peters D Michigan D+1.3 Mark Warner D Virginia D+0.1 Jeanne Shaheen D New Hampshire R+1.7 Thom Tillis R North Carolina R+5.1 Joni Ernst R Iowa R+5.8 Martha McSally R Arizona† R+9.3 David Perdue R Georgia R+11.8 Dan Sullivan R Alaska R+14.9 Cindy Hyde-Smith R Mississippi R+15.4 John Cornyn R Texas R+16.9 Lindsey Graham R South Carolina R+17.2 Bill Cassidy R Louisiana R+17.3 Steve Daines R Montana R+17.7 — R Kansas R+23.3 Mitch McConnell R Kentucky R+23.3 Ben Sasse R Nebraska R+24.0 Tom Cotton R Arkansas R+24.4 Doug Jones D Alabama R+26.8 — R Tennessee R+28.1 Shelley Moore Capito R West Virginia R+30.5 Mike Rounds R South Dakota R+30.6 James Inhofe R Oklahoma R+33.9 James Risch R Idaho R+34.9 Michael Enzi R Wyoming R+47.4 * Partisan lean is the average difference between how a state or district voted and how the country voted overall, where 2016 presidential election results are weighted 50 percent, 2012 presidential election results are weighted 25 percent, and results from elections for the state legislature are weighted 25 percent. † Special election Sources: U.S. Senate, The New York Times

Second, whomever New Mexico Democrats put up to replace Udall will likely benefit from running in a presidential year, thanks to the rise of straight-ticket voting. In 2016, for instance, all 34 states with a Senate race backed the same party for both the president and the Senate. And New Mexico has voted Democratic in six of the past seven presidential elections. George W. Bush was the last Republican presidential candidate to win the state, carrying it by less than 1 point in 2004. In 2016, President Trump lost it by 8 points, so there’s a good chance the eventual Democratic nominee will be favored there.

Third, Democrats have a potentially deep bench of candidates to pull from. They currently control all three House seats in New Mexico, so it’s possible that Reps. Deb Haaland, Ben Ray Lujan and Xochitl Torres Small could turn their eyes to the Senate. The Washington Post named all three as “potential successors,” but the representatives did not respond to FiveThirtyEight’s request for comment. Another possible candidate that both the Washington Post and Politico named was state Attorney General Hector Balderas, who ran for the Senate in 2012, but lost in the Democratic primary 59 percent to 41 percent to then-Rep. Martin Heinrich, who is now New Mexico’s other senator. Politico also suggested Secretary of State Maggie Toulouse Oliver might run.

As for who the GOP might pick to run, Politico named former Rep. Steve Pearce, though he lost both a Senate race in 2008 and a gubernatorial bid in 2018; Susana Martinez, who served as the state’s governor for two terms but was unpopular when she left office in January; and former Albuquerque Mayor Rich Berry. New Mexico Political Report also mentioned former Lieutenant Governor John Sanchez and 2018 Senate GOP nominee Mick Rich as possibilities. Of course, there’s always former Gov. Gary Johnson, who was a Republican while he led the state from 1995 to 2003, but is now a Libertarian. He was the party’s presidential nominee in 2012 and 2016 and finished third in New Mexico’s 2018 Senate race with 15 percent.

Again, New Mexico is not so blue as to be out of reach under the right circumstances and with the right candidate, so the GOP would be foolish to give up on the seat. Sure, New Mexico is 7 points bluer than the nation, but keep in mind that in Maine (D+5), which is also up in 2020, Republican Sen. Susan Collins holds the seat. A Republican can win in this kind of state.

Moreover, outside of Alabama, Republicans have limited Democratic targets in 2020 — they’re defending 22 of the 34 seats up. Plus, open seats tend to be more vulnerable to the other party anyway — though the incumbent advantage has been shrinking. New Mexico last elected a Republican senator in 2002 (to this same seat) and it elected a Republican governor (Martinez) in 2010 and 2014 by wide margins. So it’s not impossible to imagine the state having a competitive race. The National Republican Senatorial Committee said that it looks forward to “fielding a strong candidate in the New Mexico Senate race.”

A strong Republican candidate is likely the first step towards Republicans making New Mexico competitive but it’s not the last one: We’ll have to wait and see how the national environment develops — and who Democrats nominate — to see if Democrats can retain their advantage in New Mexico.