U.S.

Trump’s push to cut payroll taxes has opened a Democratic line of attack.

When Mr. Trump announced that he was unilaterally deferring payroll taxes to bring economic relief to struggling Americans, he and his aides thought it would allow them to frame him as pro-worker.

But the move comes with political risks. Eliminating the payroll tax could jeopardize the funding stream for Social Security, which is one of the government’s most popular programs, providing benefits to about 65 million people.

The president has given Democrats an opening to raise Social Security cuts as an issue in the final months of an election in which his support among older voters already appears to be shaky.

On Monday, Mr. Biden capitalized on the opportunity. “Donald Trump said that if he’s re-elected, he’ll defund Social Security,” he tweeted. “We can’t let that happen.”

The Democratic National Committee amplified the line of attack the next day, blasting out a statement that highlighted “At Least 7 Times Trump Said He Will Permanently Eliminate Funds To Social Security And Medicare.”

Beyond the complicated legal questions about whether Mr. Trump can circumvent Congress by using executive actions to create his own tax-and-spend policies, and the economic debate about whether a payroll tax even helps the right people (it does nothing for the unemployed), the proposal leaves Mr. Trump juggling political priorities.

He is now balancing the potential benefits of giving working people more money in their paychecks — at least temporarily — versus undercutting his own pledge from the 2016 campaign that he would protect entitlement programs.