WASHINGTON  Michael Steele, the chairman of the Republican National Committee, sought to contain a growing furor within his party on Sunday as three Republican lawmakers questioned his effectiveness because of his suggestion that the military conflict in Afghanistan was not winnable and was “a war of Obama’s choosing.”

Senators John McCain of Arizona and Lindsey Graham of South Carolina, who serve on the Armed Services Committee, became the latest Republicans to denounce the comments made by Mr. Steele last week at a fund-raising event, where he also said the United States was on the wrong side of history in Afghanistan.

“I think those statements are wildly inaccurate, and there’s no excuse for them,” Mr. McCain said from Kabul on the ABC News program “This Week.” “I believe we have to win here. I believe in freedom. But the fact is that I think that Mr. Steele is going to have to assess as to whether he can still lead the Republican Party.”

Doug Heye, a spokesman for the Republican National Committee, declined to comment Sunday. Several party officials said Mr. Steele had spent the weekend calling Republican leaders, including Mr. McCain, to explain his remarks and try to blunt the fallout.