Conor Lamb Had All The Makings of a Front-Runner in Pennsylvania. So Why Is He

Ms. Brodie cast her vote early for Mr. Fetterman. “He doesn’t look like a guy who walked out of an Ivy League school,” she said. “He’s going to connect with different kinds of voters.”

At a recent debate, Mr. Lamb said he knew how swing voters felt about many issues. “They’re looking for stability and caution in their leadership,” he said.

But that message, with its echoes of Mr. Biden’s 2020 campaign, may be outdated.

Brendan McPhillips, who ran the Biden campaign in Pennsylvania, said Democratic voters are looking for something different: candidates committed to fighting a Republican Party they view as lurching dangerously to the right. While both Mr. Lamb and Mr. Fetterman support eliminating the Senate filibuster to pass Democratic priorities, Mr. Fetterman has gone further by making a frequent target of Mr. Manchin, the Democrat who has blocked filibuster reform.

Mr. McPhillips said that caution was the wrong message for the Democratic base today. “The stakes could not be higher,” he said. “We’re running against literal fascists. We need to reach for bolder ideas.”

From the outset, Mr. Lamb’s fund-raising couldn’t compete with Mr. Fetterman’s appeal to a national cohort of small online donors. After launching its first TV ads in March, the Lamb campaign was forced to take them off the air for almost all of April, a crucial month when voters were tuning in to the race. The campaign returned to TV late in April, and during the first week of May it spent $543,600 for ads in Philadelphia and Pittsburgh, according to AdImpact, an ad-tracking firm.

Mr. Fetterman’s TV ads have run continuously since March. He spent $537,000 in the first week of May, reaching the state’s two major cities as well as Wilkes-Barre and Harrisburg.

Some strategists said Mr. Lamb should have been aggressively attacking Mr. Fetterman in his ads — especially over a 2013 incident when Mr. Fetterman, who was the mayor of the town of Braddock at the time, brandished a shotgun to stop an unarmed Black jogger.