A top House Republican supporting President Obama’s failing trade legislation said Sunday that he’s “optimistic” about final passage but that Obama must work hard to sway fellow Democrats who helped defeat the measure.

“The president has a lot of work to do within his own party to turn this thing around,” Wisconsin GOP Rep. Paul Ryan, chairman of the House Ways and Means Committee, told “Fox News Sunday.” “I’m optimistic because I think that this can be salvaged.”

The entire measure failed Friday when the GOP-led House overwhelmingly voted against a part of the proposal, the Trade Adjustment Assistance bill, which Democrats appeared to want and that extends aid to American workers financially hurt by previous trade deals.

“They abandon this president in droves on a bill they asked for,” Ryan said. "It’s ironic. They are the ones making [Obama] a very lame duck president, his own party.”

The House voted against the legislation 302 to 123, even after Obama met with fellow Democrats on Capitol Hill to try to get their support.

The lower chamber later passed the major part of the proposal, the Trade Promotion Authority, which would give the president the authority to "fast-track" or negotiate trade deals that Congress could approve or reject, but not amend.

Labor Secretary Thomas Perez told ABC's "This Week" that the House was stuck on a “procedural hurdle” and expressed optimism about the passage of the overall legislation. He said the United State must lead on setting the rules for global trade and that this proposed trade authority is the “most progressive” in U.S. history.

The worker-assistance legislation is expected to get a second vote this week, but cannot be passed unless Obama convinces dozens of fellow Democrats to change their vote.

Obama hoped to use the authority to complete a sweeping pact with 11 Pacific Rim nations, which would constitute the economic centerpiece of his second term.

Pro-trade Republicans sided with Obama, while progressive-minded House Democrats, including many beholden to labor unions, split with the White House.

House Minority Leader Nancy Pelosi was among those to vote against the worker-assistance, despite being an ardent, long-time Obama supporter.

The California Democrat has suggested she won’t change her mind until the legislation offers “a better deal for the American people.” 

Ryan disagreed with critics of the trade agenda, saying it will, in fact, create domestic jobs and benefit small businesses, not just corporate America.

He also said failing to pass the legislation gives the impression that the U.S. is “retreating.”

“We’re going to let China write the rules?” he asked.

The GOP-led Senate has already passed the legislation, which would impact roughly 40 percent of the global economy and which Obama has indicated he would sign into law.