CONIFER, Colo. — As Democrats scramble for elusive Republican defectors so they can take charge of President Trump's impeachment trial and summon witnesses to Capitol Hill, it would seem logical to look west to the freshman senator from Colorado.

Young, relatively moderate and with a proven reputation for independence — he didn’t vote for Trump in 2016 — Cory Gardner faces a tough reelection this year in a Democratic-trending state where revulsion toward the president runs high. Standing up to the president now could affirm that the senator remains his own man.

Yet Colorado strategists on either side of the aisle and nonpartisan analysts all agree: Gardner is highly unlikely to break rank. And the reason reflects the reality of politics for GOP officeholders in the Trump era.

It’s embodied by voters like Pat Dolan, a committed Republican who has every intention of supporting Gardner’s reelection. Unless, of course, Gardner should dare to defy Trump.

“In that case, I wouldn’t vote for him,” said Dolan, a 68-year-old physical therapist, as he paused in a supermarket parking lot nestled among snow-draped hills on the cusp of the Rockies. “Impeachment is all about politics. Conservatives need to stay together to overcome the radical left.”

To those scanning the political horizon for Republican officeholders with the inclination to stand up to Trump, the lack of prospects can be confounding.

As the president’s impeachment trial kicks off in earnest, just three Republican senators — Mitt Romney (Utah), Susan Collins (Maine) and Lisa Murkowski (Alaska) — have expressed unease with Majority Leader Mitch McConnell’s strategy of “total coordination” with the White House.

They are considered the most likely senators to buck Trump and McConnell on the crucial questions of whether new witnesses — including, perhaps, former national security adviser John Bolton — and documents will be included. To secure a majority, Democrats need at least one more vote.

Among the likely targets are retiring Sen. Lamar Alexander of Tennessee, as well as a handful of relative moderates facing reelection in swing states, including North Carolina and Arizona.

Gardner is perhaps the most vulnerable Republican of all this year, seeking a second term in a state Trump lost by nearly five points in 2016. Colorado has only shifted further left in the time since as younger, more liberal voters have flooded in and Democrats have tipped a registration deficit in their favor.

But rather than run away from Trump as the evidence mounts that he used his office to seek personal political gain, Gardner has drawn nearer.

What little he has said about impeachment — advisers acknowledge he is being conspicuously quiet on the issue — has been critical, describing the process as “a total circus.” Having already endorsed Trump’s reelection, the 45-year-old has shown no inclination to bow to Democratic demands for what they describe as the basic ingredients of a fair trial.

The choice reflects the hyperpartisan backdrop as a presidential impeachment moves to the Senate for only the third time in American history: Even in a state where voters are famously independent and where demographics favor the Democrats, Republicans believe they have little to gain politically by swimming against the Trump tide.

“Gardner has made a calculus: The Republican base is more necessary to his reelection than being that profile in courage who would try to persuade the persuadable middle,” said Kyle Saunders, a political science professor at Colorado State.

Strategically, Saunders said, that make sense: Colorado has more unaffiliated voters than it has either Democrats or Republicans. But he estimated that only up to 10 percent of the electorate is truly up for grabs, with opinions about Trump deeply entrenched on either side.

While a significant majority of Coloradans disapprove of Trump’s performance, Gardner will need Republicans, who are nearly unanimous in their support of the president, if he has any hope of keeping his seat.

“If he takes on Trump now,” Saunders said, “he demobilizes the base and has absolutely no chance.”

Sticking with the president offers its own peril, allies acknowledge.

“Cory’s got a tough race. The odds are 50-50 — at best,” said Dick Wadhams, a veteran Republican strategist in Colorado and a friend of Gardner’s. “There’s no doubt about it: Trump is a liability.”

The last time Gardner ran — scoring a narrow upset against the incumbent Democrat, Mark Udall — Trump was a New York real estate executive and reality television star. Gardner, then a second-term congressman, ran as a politically nimble “new kind of Republican” who would stand up to GOP leadership.

“When my party is wrong, I’ll say it,” Gardner told viewers in an ad that aired during the closing weeks of the 2014 campaign.

Two years later, Gardner made good on that vow, rescinding his endorsement of the then-Republican nominee for president after a video surfaced of Trump boasting how he had groped and kissed women without their consent. Gardner urged the future president to drop out and said he would write in Mike Pence’s name rather than cast a ballot for Trump.

Since Trump’s victory, Gardner has occasionally broken with the president; he was critical, for instance, after Trump’s “both sides” treatment of the white supremacist march in Charlottesville. But on most issues, Gardner has fallen into line, voting with the president’s position nearly 90 percent of the time and refraining from any stands that might draw Trump’s notorious ire on Twitter.

“Cory Gardner has chosen a path, and he’s very likely to stick with it: blind allegiance to Donald Trump,” said Craig Hughes, a Democratic strategist who managed Michael F. Bennet’s winning 2010 Senate campaign. “There are places where such a path might make more sense. Here, it’s going to cause real problems.”

The object of Gardner’s strategy, Hughes surmised, has been to avoid a primary challenge on his right flank. That appears to have been successful, with no serious competition in sight.

But Gardner — whose office declined an interview request for this article, as it has with nearly all impeachment-related media queries in recent months — still faces a mortal threat to his Senate career.

In November, he is likely to be pitted against Democrat John Hickenlooper. The popular former governor has already signaled that he will hammer the senator for his ties to a president who, polling shows, is deep underwater with Colorado voters.

Hickenlooper has called for Gardner and other senators to allow fresh impeachment witnesses and documents, saying that “a trial without witnesses and evidence isn’t a trial at all — it’s a sham.”

Should Gardner choose to rebel against the White House and vote with Democrats on those issues, “it would be an opportunity for him to recast his image,” Hughes said.

But a visit to Jefferson County, a traditional Colorado bellwether where Denver’s western suburbs begin their jagged ascent into the Rockies, shows why that’s unlikely.

Gardner and Udall fought to a virtual draw in the county in 2014. Two years later, Hillary Clinton beat Trump comfortably here. And in 2018, Democrats swamped Republicans across the board.

All the while, young, well-to-do transplants from the city — as well as from California, Illinois, New York and beyond — have fueled a boom that has housing developments and shopping centers sprouting from seemingly every turn in the twisty hillside roads.

The changes mirror those being felt statewide, nudging Colorado even further into the Democrats’ column.

But far from pushing Gardner toward a more centrist path — and away from his alignment with Trump — Republicans in Jefferson County are urging him to stick as closely as possible to the president at a time when Democrats are pushing for his ouster, said Denise Mund, chair of the local GOP.

“The Republicans I know think this thing is all made up,” Mund said. “It’s political, it’s mean-spirited and it’s not based in fact. I don’t think the president did anything wrong.”

Mund said some local Republicans consider Gardner too willing to compromise, and she has raised concerns with him when his votes have been out of sync with Trump’s wishes.

But on impeachment, she said she has no fear that the senator will step out of line.

“I don’t think Cory’s going to go there,” said Mund, who spoke at the party’s local headquarters, an office filled with “Keep America Great” ball caps and T-shirts that she said sell out almost as quickly as she can order them.

What animates the Trump base, however, has been alienating to voters who gave Gardner a chance in 2014 but who dislike the president.

It has also energized progressives like Linda Kahananui, a semiretired teacher who was rushing home from the grocery store one recent afternoon so she could write Gardner a letter demanding he hold Trump accountable for “degrading the office of the presidency.”

She had little hope it would change the senator’s mind.

“The only thing Republicans care about is retaining their power,” she said. “They don’t have the courage to stand up to the cult of Trump.”