Rep. Paul Ryan of Wisconsin, the Republican vice presidential nominee, came under intense fire from Democrats on Tuesday before his return to Washington and Congress for the first time since his elevation to the presidential ticket.

With Congress back for its first full day of a brief fall session, Democrats used the moment to attack Ryan’s long-standing proposal to reshape federal entitlement programs, as well as some of his recent statements on the campaign trail.

From floor speeches to news conferences, Democrats used every chance to poke at the House Budget Committee chairman. For the second straight day, Senate Majority Leader Harry M. Reid (D-Nev.) lampooned Ryan’s erroneous claim that he ran a marathon in less than three hours. Reid suggested that Ryan’s misstatement was intentional and compared it to what he called “obstruction” by Senate Republicans.

“I mean, you talk about jiggling your marathon time. That’s right up there with that,” Reid told reporters Tuesday afternoon.

Ryan spokesman Brendan Buck responded to the criticism, saying, “President Obama should tell his friends in Congress to focus their attention on creating jobs and stopping his devastating defense cuts.”

House Republicans defended Ryan, who has become the most influential thinker among congressional Republicans and is widely admired by rank-and-file GOP members. Speaker John A. Boehner (Ohio), in a closed-door meeting with Republicans, pointed to Ryan’s elevation as an affirmation of the House GOP’s influence.

“Paul Ryan’s selection by Governor Romney validated all the work House Republicans have done over the past 19 months,” Boehner told his colleagues, according to notes taken by a Republican in attendance.

During the national party conventions over the past two weeks, Ryan and his policy proposals receded from the spotlight they attracted immediately after his selection as Mitt Romney’s running mate. Democrats hope his return to the Capitol on Thursday for a vote on a short-term resolution funding the government through next spring will refocus the debate on his proposals.

The spending bill would fund the government for the first six months of fiscal 2013, which begins Oct. 1, at levels agreed to in the 2011 Budget Control Act. That law created a process for more than $2 trillion in federal savings over the next decade and increased the Treasury’s ability to borrow money.

It’s the last piece of legislation likely to win approval before the House and Senate adjourn next week so members can head back to their states for the fall campaign, though some farm-state lawmakers are jostling to pass a temporary drought-relief bill.

Democrats this week have focused floor speeches on Ryan’s budget proposal, which would achieve trillions of dollars in savings by turning Medicaid into a block-grant program run by the states and by creating a private insurance option for Medicare. Sen. Richard J. Durbin (Ill.), the No. 2 Democratic leader, used his floor speech honoring victims of the Sept. 11, 2001, terrorist attacks to criticize Ryan for not “asking some sacrifice” — such as reduced military spending or higher taxes on the wealthy.

“Unfortunately, Congressman Ryan’s budget does not pass the basic test of arithmetic,” Durbin said.

Republicans dismissed the Democratic complaints about Ryan, suggesting that the Senate had been negligent for not approving its own budget. GOP leaders said voters will reward them for trying to tackle the debt issues.

“Only the House has taken action to stop . . . these looming threats,” Boehner told his colleagues. “We need to take our message straight to the people.”