Republican members of Congress "need" to participate in future efforts to reform healthcare, lest they put themselves in a politically poor position, a leading House Democrat said Wednesday.

Democratic Caucus Chairman John Larson (D-Conn.) said that the Republicans' strategy of calling for a repeal of the newly-passed healthcare law will force them to make politically untenable arguments during their fall reelection campaigns.

"Republicans need [to participate]," Larson said on ABC's "Top Line webcast. "They're out there talking about repeal. They don't want to be talking about repeal of children's benefits."

GOP leaders have doubled down on their opposition to the Democrats' healthcare law that passed without their support Sunday. Some leaders have called for an outright repeal of the bill while others have called for incremental changes to scale back portions of the new law.

While Republicans argue that campaigning on the healthcare overhaul's passage in the fall midterms will doom the Democrats, Larson expressed confidence that it will be a political winner. 

"I think sometimes good policy, which this is, becomes good politics," he said. "Members are going to be going back to their districts and talking about this...The members have received great plaudits for the passing of this bill."

Larson said that Republicans would do better if they offer their own amendments and alternatives and cooperate with Democrats if and when additions to the bill are made down the line.

"This is the foundation, this is the start, there is going to be a lot more action for correction," the Connecticut Democrat said. 

But Republican Sen. John McCain (R-Ariz.) said this week that members of his party will refuse to work with their colleagues on the other side of the aisle this year because they "poisoned the well in what they've don" with the healthcare bill.

The 2008 GOP presidential nominee later backed off slightly from his remarks.