Former President Trump’s Monday assault against Joe O’Dea, the GOP’s Senate nominee in Colorado, is angering Republicans while leaving them wondering if he cares about the party winning back the majority in the upper chamber.

O’Dea, a pro-abortion rights moderate whom Democrats spent $4 million against in the primary, was already in an uphill fight against Sen. Michael Bennet (D-Colo.).

Now Republicans worry any chance he has of pulling off an upset are being extinguished by Trump, prompting frustration and exasperation with the ex-president.

“It certainly is not [helpful],” Sen. Kevin Cramer (R-N.D.), a Trump ally, told The Hill. “I would hate to see O’Dea lose to Sen. Bennet by a few votes just because Donald Trump urged Republicans not to vote and we came up short of the majority by one senator.”

“If [Sen.] Mitch McConnell [R-Ky.] opposed every Republican nominee who criticized him publicly, we wouldn’t stand a chance,” Cramer continued, referring to the Senate minority leader. “The nation has to be more important than individual personal offenses.”

In a post on his social media site, Trump labeled O’Dea a “RINO,” or “Republican in name only,” and said that “MAGA doesn’t Vote for stupid people with big mouths.”

The barb came in response to O’Dea saying that he would not support the former president if he ran again in 2024 and that he would actively campaign against him.

Adding to the trouble, the remarks came at the worst possible time for O’Dea as ballots started to be distributed in the state on Monday.

One GOP strategist involved in Senate contests likened Trump’s attack on O’Dea to his rhetoric surrounding the Georgia runoffs following his election loss in 2020, which many Republicans believe helped suppress turnout among Republicans.

“If O’Dea is literally the difference between a GOP majority and minority, you think about the profound policy ramifications that come along with that. To think you can be anywhere right of center and be willing to mortgage on a Republican majority just because someone says not nice things about you is pretty revealing,” a second GOP operative involved in Senate races said.

“It’s all about this fealty to him, and you don’t have to be a mathematician to realize how that went in Colorado two years ago,” the strategist added, referring to President Biden’s 14-point win over Trump in the state.

While O’Dea is considered one of the GOP’s best Senate recruits this cycle, he still faces a steep climb to defeat Bennet, a two-term incumbent, in what has become a blue state. No Republican has won a statewide general election in Colorado since 2014, when former Sen. Cory Gardner (R-Colo.) defeated former Sen. Mark Udall (D-Colo.), which also led to GOP wins in the offices of state attorney general and secretary of state.

“To win a state like Colorado, you need everyone open to you to vote for you. Any sort of shooting inside the tent has potentially profound consequences,” the second GOP strategist said. “You need everyone.”

In a statement on Monday in response to the ex-president, O’Dea said that he is “a construction guy, not a politician.”

“President Trump is entitled to his opinion but I’m my own man and I’ll call it like I see it. Another Biden, Trump election will tear this country apart,” O’Dea said, adding that Florida Gov. Ron DeSantis (R), Sen. Tim Scott (R-S.C.), former Secretary of State Mike Pompeo and former U.S. Ambassador to the United Nations Nikki Haley “would be better choices.”

“These elections should be focused on Joe Biden’s failures – supercharged inflation, a broken border, rampant crime, a war on American energy – not a rehash of 2020,” O’Dea added. “America needs to move forward.”

According to a Marist University survey taken earlier this month, Bennet led O’Dea by 6 percentage points.

The Senate Leadership Fund, a group run by top allies of McConnell, donated $1.2m to an O’Dea super PAC on Oct. 7, which went toward a two-week ad buy in Denver. The group has not ruled out making further investment in the race and is continuing to monitor it, according to an SLF spokesperson.

Given the margin to overcome, some Republicans are skeptical that Trump’s comments will make much of a dent when all is said and done. They note that O’Dea has been vocal about his opposition to the former president for months and believe the state’s antipathy for Trump will render his comments relatively null and void.

“O’Dea has been very clear that he is a Republican. He is a businessperson. He has been very clear about what he thinks about Trump,” said one GOP operative with Trump ties. “I don’t think it’s going to change things for O’Dea either. It’s a wash. It gets Trump some clicks and some headlines. It gets O’Dea the same. … It’s a self-fulfilling prophecy. O’Dea says he doesn’t like Trump. Trump bashes O’Dea. O’Dea can say ‘see?’”  

The operative also pointed to Trump’s continued push to install loyalists throughout the GOP ranks, including at the state party and county level, as a likely reason for the Monday statement. 

“Trump wants the party to reflect him,” the strategist added.