Colorado could have a competitive U.S. Senate race on its hands.

That’s the judgment of the election forecasters at the Cook Political Report, which on Thursday moved the state one notch to the right – from “Likely Democrat” to “Lean Democrat.”

Still a step away from toss-up status, the rating shift reflects increased attention by both national parties on Democratic U.S. Sen. Michael Bennet’s bid for a third term against Republican Joe O’Dea, a wealthy construction company CEO and first-time candidate. 

The move coincides with Cook downgrading to a toss-up the GOP’s chances of winning a majority this fall in the 50-50 Senate, where Democrats hold the gavel owing to the tie-breaking vote wielded by Vice President Kamala Harris.

In part, Cook’s Jessica Taylor says, that’ because Republicans have nominated “weak, divisive candidates” in several of the GOP’s must-win states, including Mehmet Oz in Pennsylvania and Blake Masters in Arizona. Colorado’s rating change appears to be partially a byproduct of the GOP’s less-than-stellar standard bearers in other states once considered riper targets, leaving national Republicans strategists “hav(ing) to find other plausible races.”

Cook cites Senate Republican Leader Mitch McConnell’s remarks last month calling O’Dea “the perfect candidate” for Colorado and a declaration that national Republicans are going to get involved in the race. Democrats, meanwhile, “acknowledge this isn’t in the bag and is closer than many people think,” according to an unnamed Colorado GOP strategist quoted by Cook. The same strategist acknowledges that key constituencies could be difficult for the Republican to carry unless the election is primarily about the economy and not abortion or other social issues.

The adjustment comes with a caveat that Bennet doesn’t likely face the same uphill battle for reelection as fellow Democratic incumbent Maggie Hasan in more competitive New Hampshire, a more favorable state for Republicans this year.

In addition to changing Colorado’s category, Cook moved two states to the left: the open, Republican-held Pennsylvania seat from “Lean Republican” to “Toss-up,” and Utah, where incumbent Republican Mike Lee faces a challenge from Democratic-backed unaffiliated candidate Evan McMullin, from “Solid Republican” to “Likely Republican.”

Colorado Republicans applauded the state’s more competitive rating.

“This ratings shift proves what we all know: Michael Bennet is vulnerable and will be beaten in November,” said state GOP executive director Joe Jackson in a statement. “Bennet has chosen to stand fully with Joe Biden and Chuck Schumer instead of fighting for the people of Colorado. Joe O’Dea is that fighter and a candidate who won’t be beholden to Biden and the far-left radicals in Washington.”

Bennet’s campaign manager told Colorado Politics the campaign is taking the news in stride. 

“Michael’s campaign is prepared for a competitive midterm election cycle, and Michael proved he can run and win close elections before,” Justin Lamorte said in a text message. “Michael’s campaign entered the general election with a 10-to-1 cash advantage, has held grassroots events with big, energized crowds across the state, and is communicating about his strong and growing records of delivering for working people, lowering costs and protecting Colorado’s public lands and our way of life. We’re doing the work it takes to win in November.”

Cook moved Colorado from “Solid Democrat” to “Likely Democrat” in February based on a worsening environment for Democratic incumbents, though the Supreme Court’s decision overturning Roe v. Wade in June, coupled with falling gas prices and a string of recent legislative wins — including bipartisan gun control and veterans’ health care measures — could have reshaped what had looked like an approaching Republican rout.