HOUSTON — Former Vice President Joseph R. Biden Jr. clung tightly to the legacy of the Obama administration in a Democratic primary debate on Thursday, trying to offer himself as a stand-in for the former president as an array of progressive challengers, led by Senators Elizabeth Warren and Bernie Sanders, brandished more daring policy promises and questioned Mr. Biden’s political strength.
Facing all of his closest competitors for the first time in a debate, Mr. Biden, the Democratic front-runner, repeatedly invoked President Barack Obama’s name and policy record as a shield against rivals who suggested his own record was flawed, or implied his agenda lacked ambition. On health care, immigration, foreign wars and more, Mr. Biden’s central theme was his tenure serving under Mr. Obama.
By constantly invoking Mr. Obama, a beloved figure among Democrats, Mr. Biden sought to mute the ideological and generational divisions that have left him vulnerable in the primary race. To voters who might see him as a candidate of the past, Mr. Biden seemed to counter that the past was not so bad.
In an early exchange over health care, Mr. Biden referred to Ms. Warren’s support for Mr. Sanders’s “Medicare for All’’ plan. “The senator says she’s for Bernie,” Mr. Biden said. “Well, I’m for Barack — I think the Obamacare worked.”