Utah Democrats are supporting an independent conservative, Evan McMullin, in a last-ditch effort to defeat an incumbent U.S. senator, Mike Lee, in his bid for re-election in November. The effort could backfire on the Democrats.

For an independent, Mr. McMullin is doing unusually well in the polls. The latest, conducted by Dan Jones and Associates between July 13 and July 18, showed Mr. McMullin trailing with 36 percent support to Mr. Lee’s 41 percent.

In a country where third-party candidates rarely get elected or even secure a significant portion of the vote, an independent candidate polling within striking distance of an incumbent senator is raising some eyebrows.

Mr. McMullin’s popularity is due in large part to the decision by Utah Democrats to endorse him. At their April convention, they voted 57 percent to 43 percent to throw their support behind Mr. McMullin instead of a homegrown Democrat, Kael Weston.

“Today we took an important step in building a new coalition of Democrats, Republicans and independents to change our broken politics,” Mr. McMullin tweeted at the time.

A professor of political science at the University of Utah, James Curry, argues that the move by Utah Democrats to back Mr. McMullin  was “a calculated decision by party leadership.”

Mr. McMullin, a conservative who ran for president in 2016 and served as a CIA agent for nine years, stands a better chance of winning a statewide election than most Democrats would, according to Mr. Curry.

Mr. McMullin is a vocal critic of both Mr. Lee and of the senator’s relationship to President Trump, against whom Mr. McMullin campaigned in 2016. His strategy appears to be to build a coalition of Democrats, independents, and Republicans who dislike both Messrs. Lee and Trump.

“I need to maintain my independence in order to represent this coalition I’m building — I’ve asked the Democrats to join me, I’ve asked Romney Republicans to join me, independents, the United Utah Party, and they are. They’re joining this coalition,” Mr. McMullin said on The Chuck ToddCast, referring to Utah’s other U.S. senator, Mitt Romney.

Utah has historically been somewhat lukewarm toward Mr. Trump. In 2016, the businessman won the state with 45.5 percent of the vote. A lack of united opposition might have put him over the top that year. Senator Clinton and Mr. McMullin won 27.5 percent and 21.5 percent of the vote, respectively. 

In 2020, Mr. Trump won Utah with 58 percent of the vote, compared to President Biden’s 37.6 percent. These results, however, are far from telling the whole story.

Mr. Romney, a vocal critic of Mr. Trump who voted to convict the president in the second impeachment trial, was re-elected in 2018 with 70 percent support statewide. 

Polling conducted by Deseret News and the Hinckley Institute in May confirms that Mr. Romney remains popular, with 51 percent of registered voters in Utah saying that he “best represents” their political views, compared to 37 who reported that Mr. Trump did.

Mr. Curry argues that Mr. McMullin’s campaign is attempting to capitalize on Utah’s middling support for Mr. Trump and Mr. Lee’s relationship with him in order to clinch a victory in November.

Mr. McMullin himself has telegraphed this strategy in his statements and campaign ads, which attack Mr. Lee for his connection to Mr. Trump.

One of Mr. McMullin’s ads claims that Mr. Lee was “only one of two senators in on the scheme,” in reference to Mr. Trump’s attempts to overturn the results of the 2020 election.

“We can’t have Senators who play footsie with efforts to overturn our elections,” Mr. McMullin told FOX 13 Utah.

While Mr. Trump is not as popular in Utah as he is in other Republican states, Mr. Curry argues that Mr. McMullin’s strategy is unlikely to work.

“McMullin doesn’t have a zero percent chance of winning but his chances are still slim,” he tells the Sun. “Mike Lee still has a five- or six-point lead, which in the context of a Utah Senate race sounds tight, but other places would seem pretty big.”

Mr. Curry notes that independent candidates tend to poll best in the summer before slumping as the year progresses and voters return to their regular partisanship.

He also argues that Utah Democrats’ decision to back Mr. McMullin’s candidacy will likely backfire, possibly causing them to lose further influence in Utah politics.

“One point that’s getting missed in this on the Democratic side is that now they don’t have a Democrat at the top of the ballot,” Mr. Curry said. “That’s a really important thing to have in order to drive turnout.”

He argues that all that most Democrats have in common with the conservative Mr. McMullin is their disapproval of Messrs. Trump and Lee, and that might not be enough to get them to the polls.

“If you’re a Democratic voter in the state of Utah you don’t really have a choice to represent you in the Senate,” he said. “If you’re a  Democrat are you really happy with this option?”