In an election cycle in which many Republican Senate hopefuls have staked their names on their relationships to President Trump, the GOP nominee in Colorado, businessman Joe O’Dea, is cutting against the grain.

In the spring, Colorado was on the list of states that the Republicans looked poised to flip, as rising inflation and President Biden’s plunging popularity led to whispers about a red wave in the November general election. Now, that wave appears to be petering out.

The relatively small amount of money that the National Republican Senatorial Committee spent in Colorado — about $46,000 so far — has been held up as an example of the GOP’s lack of ambition during this election cycle, and as perhaps a strategic blunder.

The gripe was that the Republican Party spread itself too thin in the beginning of the election cycle, spending money on races in places that they never stood a chance of winning, like Colorado and Washington.

In Colorado, Mr. O’Dea is running to unseat Senator Bennet, the incumbent Democrat, and at the moment his odds don’t look good. The most recent polling, from late July, showed Mr. O’Dea 7.7 points behind Mr. Bennet.

In June, though, polling by the Global Strategy Group showed Mr. O’Dea down by 13 points.

The dean of the School of Public Affairs at University of Colorado at Denver, Paul Teske, argues that this Senate race is a last stand of sorts for Republicans, who have seen a dramatic loss of support in Colorado over the past 20 years.

“Bennet’s a pretty formidable candidate, has been in two terms, and has amassed a pretty good amount of money,” Mr. Teske tells the Sun. “I can see why the NRSC could be a little weary.”

He also identified Mr. O’Dea as a highly electable candidate — a new man in politics who has not pinned his identity within the GOP to Mr. Trump.

“Compared to Herschel Walker or Dr. Oz, O’Dea is cut from that same cloth in that he is new to politics,” Mr. Teske tells the Sun, referring to GOP Senate candidates from Georgia and Pennsylvania. “A winning Republican candidate in Colorado has to appeal to moderates and independents and keep the base — his only chance is taking a moderate stance.”

Mr. O’Dea has publicly said he hopes Mr. Trump doesn’t run in 2024, and has refused to entertain the idea that President Biden stole the 2020 election. He even criticized his primary opponent for his talk about 2020 and the past, saying, “I’m not going to focus on that.”

Mr. O’Dea has also staked out moderate positions on issues like abortion, saying he would vote to codify the provisions of Roe v. Wade into law.

It is such positions that have propelled Mr. O’Dea in Colorado, a state that allows independent voters to vote in party primaries. In the primary, he defeated a Trump-aligned candidate backed by the state’s GOP, Congressman Ron Hanks.

A political scientist at Colorado College, Robert Loevy, argues that Mr. O’Dea’s attempt to capture independents was the right move for Colorado, and something Republicans in other states should emulate.

“He has worked hard to be an acceptable place to put an anti-Biden, anti-Democratic vote,” Mr. Loevy tells the Sun, adding that these moderate stances make Mr. O’Dea just about the best candidate that Republicans could have hoped for in Colorado.

Mr. O’Dea’s prospects, however, are declining as the national environment shifts away from the Republicans and the red wave seemingly evaporates. Still, he has successfully cultivated an anti-Biden coalition, something that other Republican Senate candidates have struggled to do.

While it does look like Mr. O’Dea will likely fail in his mission to retire Mr. Bennet, this would be easily attributable to the environment in Colorado, which is on the verge of becoming a true-blue state.

Behind his likely defeat, Mr. O’Dea has carved out a model for what a relatively successful Republican campaign can look like without being dominated by Mr. Trump and without alienating independent voters.