DECORAH, Iowa — Pete Buttigieg escalated his attacks on Vice President Joseph R. Biden Jr. and Senator Bernie Sanders of Vermont on Thursday, taking direct aim at the two leading presidential candidates as he tries to gain ground before the Iowa caucuses.
Mr. Buttigieg, the former mayor of South Bend, Ind., dismissed disputes between the two men over the Iraq war and Social Security as a kind of politics of the past, saying their debates repeat the party’s mistakes.
“This is not the time to get caught up in reliving arguments from before,” he told several hundred people gathered in a hotel ballroom in Decorah, Iowa. “The less 2020 resembles 2016 in our party, the better.”
In his stump speeches and in answers at campaign events, Mr. Buttigieg has steadfastly avoided direct hits on his opponents, instead drawing opaque contrasts that reporters and the most engaged Democratic voters have understood to be whacks at Mr. Biden and Mr. Sanders.
His decision to call out his chief rivals by name underscores the pressure Mr. Buttigieg faces for a top-two finish, and signals an intensification of a race that has been relatively polite for nearly a year, with the candidates often saving their toughest hits for the more controlled environment of the debate stage.
With the race entering its final days before caucusing on Monday, and the top candidates locked in a tight race, Mr. Buttigieg’s closing argument may mark the start of more direct clashes.
“I hear Vice President Biden saying that this is no time to take a risk on someone new,” he said. “But history has shown us that the biggest risk we could take with a very important election coming up is to look to the same Washington playbook.”
Mr. Buttigieg also argued that Mr. Sanders’s plans for “Medicare for all” and free college go farther than what most in the Democratic Party can support.
“I hear Senator Sanders calling for a kind of politics that says you got to go all the way here or nothing else counts,” he said. “It’s coming at a moment when we actually have a historic majority, not just a line around what it is we’re against, but agreeing on what it is we’re for.”
The comments from Mr. Buttigieg are in keeping with his effort to paint himself as the type of transformational figure he argues neither Mr. Biden nor Mr. Sanders can be because of their decades of experience in Washington’s political battles.
For days the Buttigieg campaign has been sending out fund-raising appeals warning that it would be too “risky” to nominate Mr. Sanders and suggesting that President Trump wants to face the Vermont senator in November.
“We risk nominating a candidate who cannot beat Donald Trump in November — and Trump’s team knows this,” Mr. Buttigieg’s deputy campaign manager, Hari Sevugan, wrote in one of the emails on Tuesday. “They’re working to make sure it happens.”
It is a more aggressive version of the political contrast he has sought to paint in Iowa since Labor Day, when he was the first of the leading candidates to begin broadcasting TV ads in the state. He highlighted those messages with subtle argument against the progressive politics of Mr. Sanders and Senator Elizabeth Warren of Massachusetts, who at the time was the state’s polling leader.
Though Mr. Buttigieg began his TV ad campaign in Iowa first, there are fewer ads on the air for him in the final week before the caucuses than there are for his competitors. Mr. Buttigieg is being outspent by Mr. Sanders, Ms. Warren and the super PAC backing Mr. Biden — though with the local airwaves saturated by political ads there can be just as much value in making news by going on the attack on the stump as there is in buying more TV time.
Pressed by reporters earlier this week, Mr. Buttigieg had resisted calling Mr. Sanders a risk himself and would not say if he believed Mr. Sanders could beat Mr. Trump. On Thursday, he cast his new remarks as airing an “honest and respectful” difference between the visions of the three men. He also acknowledged that he needs a “strong finish” in the Iowa race.
“This is certainly the moment when folks are choosing, and I want to make sure everyone understands the choice between us,” he told reporters. “We’re competing, it’s a respectful but important competition about what the best approach is going to be.”
Yet, in a moment when many Democrats want party unity around a goal of defeating Mr. Trump, there’s a chance that Mr. Buttigieg’s harsher hits could backfire. The primary race has been notable for its lack of particularly tough attacks, with the candidates often circling one another warily even in the final days before caucusing begins.
Now that Mr. Sanders and Mr. Biden are ahead of him, Mr. Buttigieg has shifted from an argument against a progressive revolution toward one focused around his rivals’ age, albeit without explicitly calling Mr. Sanders, 78, and Mr. Biden, 77, old.
Many of Mr. Buttigieg’s campaign stops have the words “TURN THE PAGE” spelled out in large blue letters behind the stage, a reminder of both his own far younger age, 38, and the idea that he would be free of the political entanglements and baggage that he ascribes to Mr. Biden and Mr. Sanders.
A political newcomer, he argues, would have both a better chance of defeating Mr. Trump in a general election and a more unfettered mandate to enact progressive policies in Washington.
Lisa Lerer reported from Decorah, and Reid J. Epstein from Des Moines.