A top Republican lawmaker said Wednesday that the GOP has a 50/50 chance of winning back the House this fall.

Rep. Paul Ryan (R-Wis.), the ranking member of the House Budget Committee, said, though, that Republicans would have to lay out a roadmap of how they would govern — as well as guarantees of how Republicans wouldn't repeat the errors of their previous ways in the majority.

"I think we've got about an even chance of taking back the place; that's my guess," Ryan said during an appearance on CNBC.

Republicans had been ebullient earlier this year amid a flurry of polls showing them ahead in the generic congressional ballot. But some special-election losses and a narrowing of the margins in the polls have tempered some, though not all, GOP hopes going into this fall's contests.

But the GOP is still playing offense this cycle, with most Democrats conceding that losses in some seats are likely. House Republican Leader John Boehner (Ohio) has said that 100 seats are in play for his party.

"We need to give the American people an alternative — who are we, what do we believe in, what are our principles, how will we apply them and what will we do if you elect us back, and how do you make sure we won't repeat the sins of fiscal profligacy that we made last time we were in the majority," Ryan said.

"That's the kind of thing I think people want to hear from us," he added.