Washington – Days after House Republicans unveiled a road map for an overhaul of the nation's broken immigration system, one of its backers said legislation is unlikely to pass during this election year.

Rep. Paul Ryan, R-Wis., said distrust of President Obama runs so deep among Republicans that he's skeptical the GOP-led House would pass any immigration measure.

He said a plan that puts security first could only pass if lawmakers believe the administration would enforce it — an unlikely prospect given Republicans' deep opposition to Obama. "This isn't a trust-but-verify, this is a verify-then-trust approach," Ryan said.

Last week, House Republicans announced their broad concerns for any immigration overhaul but emphasized they would tackle the challenge bill by bill.

Immigration legislation is a dicey political question for the GOP. The party's conservative base opposes any measure that would create a pathway to citizenship for immigrants here illegally.

However, many in the party worry that failing to act could drive voters to Democratic candidates.

In 2012, Obama won with the backing of 71 percent of Hispanic voters.

Republicans have been trying to blame the White House for immigration legislation's failure, even before a House bill comes together.

House Majority Leader Eric Cantor said "there's a lot of distrust" in the Obama administration's willingness to enforce an immigration law.

House Republicans are pushing a piecemeal approach to immigration that puts a priority on security before considering a pathway for those here illegally to earn citizenship.

That strategy runs counter to a comprehensive bill, passed by the Senate seven months ago with bipartisan support, that includes a long and difficult pathway to citizenship.

The White House, meanwhile, returned to its position that any legislation must include a way for those living here illegally to earn citizenship and that the system cannot divide Americans into two classes — citizens and noncitizens.

"We ought to see a pathway to citizenship for people," White House chief of staff Denis McDonough said Sunday. "We don't want to have a permanent separation of classes or two permanent different classes of Americans in this country."

Last week, Obama suggested that he's open to a legal status for immigration that falls short of citizenship, hinting he could find common ground with House Republicans.

"I'm going to do everything I can in the coming months to see if we can get this over the finish line," he said.

Obama's flexibility was an indication of his desire to secure an elusive legislative achievement before voters decide in the fall whether to hand him even more opposition in Congress.

McDonough said the White House remains optimistic that legislation that includes citizenship could reach the president's desk this year.

Not so, countered Ryan, the GOP's vice presidential nominee in 2012. "Here's the issue that all Republicans agree on: We don't trust the president to enforce the law," he said.

Ryan spoke to ABC's "This Week." Cantor was interviewed on CBS' "Face the Nation" and McDonough appeared on NBC's "Meet the Press" and on CBS.