WASHINGTON — Representative Beto O’Rourke’s blockbuster fund-raising in his race to unseat Senator Ted Cruz of Texas is colliding with a widening deficit in polls, bringing long-simmering tensions into public view between Democrats who believe Mr. O’Rourke should share his bounty with better-positioned candidates and others who say his only obligation is to maximize his own chances.
Mr. O’Rourke announced Friday that he had raised over $38 million in the last three months alone, a staggering sum for a statewide race and the most of any Senate candidate in history. But a new poll completed Thursday night by The New York Times Upshot and Siena College indicated that Mr. Cruz now leads Mr. O’Rourke by eight percentage points, 51 percent to 43 percent, with a margin of sampling error of plus or minus 3.6 points.
This convergence illustrates both the remarkable rise of Mr. O’Rourke, previously a little-known congressman from the border city of El Paso, into a national Democratic leader and the fundamental difficulty of attempting to win as a progressive in Texas.
But Mr. O’Rourke is also emerging as a small-dollar fund-raising force — one whom many supporters hope will run for president, win or lose — at the moment his party is seeing its prospects for retaking the Senate dim in the aftermath of the protracted clash over the Supreme Court nomination of Justice Brett M. Kavanaugh.
With red-state Democratic Senate candidates dropping in the polls, a growing chorus of party officials is suggesting that Mr. O’Rourke share his bulging war chest with other candidates and the Democratic Senatorial Campaign Committee.
“It’s great that O’Rourke has inspired so many people and raised so much money, and if he can spend it all effectively in Texas, he is well within his rights to do so,” said Matthew Miller, a veteran Democratic strategist and Texas native. “But he could have a huge impact for the party by sharing some of it with the D.S.C.C. so it could be spent in states where candidates just need a little extra to get over the hump.
“It will be bad for everyone, Beto included, if he finishes his race with money in the bank when that money could’ve helped elect Democrats in Missouri, Tennessee or North Dakota,” Mr. Miller added.
Aggravating Democrats further are reports that Mr. O’Rourke — not through any direction of his own — is receiving money from grass-roots supporters in states that also have competitive races. This has included word of an upcoming O’Rourke fund-raiser in Missouri, where Senator Claire McCaskill, the incumbent Democrat, is straining to survive a challenge from Josh Hawley, the state’s Republican attorney general.
Mr. Miller cited the 2008 election, when now-Senator Mark R. Warner of Virginia was rolling to victory and gave $500,000 to the party committee in a year when they picked up eight seats.
Yet other Democrats are quick to note that party candidates who are running more cautious and centrist campaigns in conservative states are faring no better than the liberal Mr. O’Rourke. In Tennessee former Gov. Phil Bredesen, the Democratic nominee for the Senate, came out in support of Justice Kavanaugh but has seen his standing in the polls plummet.
And, these Democrats say, Washington-based strategists are in denial about both why Mr. O’Rourke has raised so much money and what it says about the party’s fund-raising culture. Mr. O’Rourke has harnessed social media to viral effect, live-streaming much of his waking life, from rallies to burger runs.
“People will, because of the internet and because of how people now access information, donate to any candidates and causes that inspire them most,” said Jon Favreau, a former speechwriter for Barack Obama who has been an outspoken supporter of Mr. O’Rourke. “The idea that there is some entity in D.C. that can direct the fund-raising for how people give is thinking that is so 10, 20 years ago.”
The deeper tension, which Democrats will mostly only discuss privately while Republicans say it publicly, owes to the question of Mr. O’Rourke’s ultimate ambitions: Does he believe that an unapologetically liberal campaign in a traditionally red state is the best way to win in 2018? Or might he achieve political martyrdom at the hands of a senator Democrats hate and then seek a bigger platform?
“Clearly he’s not running for the United States Senate from Texas,” Senator John Cornyn of Texas said Friday on Laura Ingraham’s talk radio show, adding: “My only suspicion, Laura, is he’s running for the Democratic nomination for president in 2020.”
Mr. O’Rourke has denied any interest. “Oh, no, I don’t want to do that,” he said in an interview in August. “No.” On Friday, Mr. O’Rourke and his campaign did not respond to text messages about whether he would transfer any of his fund-raising haul and if he was committed to spending all his money raised on this race.
Even Texas Republicans seemed comfortable with the idea that Democrats were plowing so much money into the state.
“I’m delighted they’re wasting their money here,” said Matt Mackowiak, the chairman of the Travis County Republican Party. “Take $30 million of that and the Democrats could have won the Senate.”
Of course, there are still more than three weeks before Election Day — enough for the race to change, and then change again, given the volatility of this political moment. But The New York Times Upshot-Siena poll, and others in recent days, have suggested that Texans appear likely to stick with the Republican candidate in a state that Mr. Trump carried by nine points in 2016.
Half of the poll’s respondents said they approved of the job Mr. Trump was doing in office, and a slight majority said they would like to see Republicans retain control of the Senate in November.
As with many races throughout the country this year, the gender gap in Texas appears stark. The candidates are effectively tied among female voters, according to the poll, but Mr. Cruz holds a lead of more than 15 points with men. He also leads decisively with voters over 45.
Mr. O’Rourke has staked his campaign on an ability to make inroads with new kinds of voters. He boasts of traveling to all 254 Texas counties, even those so red “you can see them glowing from outer space,” and is trying to turn out key groups, particularly young and nonwhite voters, whose participation in the midterms tends to lag.
Among Hispanic voters in the poll, Mr. O’Rourke leads 56 percent to 37 percent — a clear advantage, but one that might be insufficient with a group that Democrats have hoped would support their candidate in even greater numbers. Mr. O’Rourke, a fluent Spanish speaker, has frequently highlighted the plight of immigrants under Mr. Trump, holding up the administration’s family separation policies at the border as a moral stain.
Even many of Mr. O’Rourke’s supporters have long understood the odds. In a follow-up interview after being contacted for the Upshot-Siena poll, John Saylor, 61, of Muleshoe, Tex., commended Mr. O’Rourke for being “out with the people,” but he acknowledged the challenges facing his candidate.
“Beto is running a great campaign,” he said. “But this is Texas.”
Liam Stack contributed reporting.