President Obama delivered remarks on the U.S. economy from Georgetown Waterfront Park in D.C. on Tuesday. In his speech, Obama responded to Republican House Speaker John Boehner's recent threat to sue the president. (Associated Press)

Striking a combative tone, President Obama on Tuesday blamed congressional Republicans with holding up his plan to replenish a nearly depleted trust fund for highway and bridge repairs.

Obama used a speech at the Georgetown Waterfront Park to urge lawmakers to pass his four-year, $302 billion transportation policy plan, which would devote $63 billion to boost the Highway Trust Fund.

“So far, House Republicans have refused to act on this idea. I haven’t heard a good reason why they haven’t acted — it’s not like they’ve been busy with other stuff,” Obama said to a chorus of laughter from a crowd of about 500 supporters.

The fund, which is fueled by the gas tax, is expected to run out of money next month, at the height of summertime infrastructure repair projects across the country.

Earlier Tuesday, Transportation Secretary Anthony Foxx warned that unless the trust fund is replenished, the administration will slow the flow of reimbursement checks to states for their federal transportation projects beginning in August. The change could delay or jeopardize projects across the country, putting up to 700,000 jobs at risk, Foxx said.

Although there is bipartisan support for infrastructure repairs, lawmakers are at odds about how to find the necessary funds and have laid out several competing proposals.

The administration’s plan, unveiled in February, would end the fund’s reliance on the gas tax by substituting savings derived from closing corporate tax loopholes and encouraging U.S. companies to repatriate offshore profits. A bipartisan proposal recently introduced in the Senate by Bob Corker (R-Tenn.) and Chris Murphy (D-Conn.) would raise the gas tax, currently 18.4 cents per gallon, by 12 cents. That bill, opposed by the Obama administration and by congressional Republicans, is unlikely to pass.

Other proposals by Republicans would find funding for the infrastructure repairs by curtailing Saturday mail deliveries or collecting online sales taxes.

Obama’s call for congressional action stands in contrast to the strategy of executive action that he has employed for a number of economic issues this year, including raising the minimum wage for employees of federal contractors and extending the cap on student-loan payments. There is only so much he can do, he has said, without Congress’s cooperation.

Yet Obama remained defiant, saying he would continue to act of his own accord on economic issues.

“Middle-class families can’t wait for Republicans in Congress to do stuff. So sue me,” Obama said Tuesday. “As long as they’re doing nothing, I’m not going to apologize for trying to do something.”

Obama’s quip came as a reference to House Speaker John A. Boehner’s announcement last week that he plans to take the administration to court for what he believes to be its excessive and unconstitutional use of executive actions.

In response to Obama’s speech, a Boehner spokesman defended the record of House Republicans, pointing to the jobs legislation that has passed under GOP leadership.

“It is Washington Democrats, led by President Obama, who are blocking help for millions of Americans still asking, ‘where are the jobs?’ ” Michael Steel said.