To some degree, the attacks on Mr. Ryan, so far an unwilling draft pick by his colleagues to replace Speaker John A. Boehner, reflect criticism of flashes of pragmatism by Mr. Ryan, the architect of his party’s conservative budget dogma.

Since the 2012 general election defeat, Mr. Ryan has indeed become more of a consensus builder and leader in the House, even as he has maintained his ideological tilt. He has largely voted for bills to keep the government operating and the debts paid when many other Republicans vote against them these days.

He was half the brain on a 2013 compromise with Senator Patty Murray, Democrat of Washington, to funnel more money to the government and avert two years of budget brinkmanship, even though two years earlier, he had refused to sit on the original committee that tried and failed to find a solution to the government’s financial problems.

Mr. Ryan moved this year to the chairmanship of the tax-writing Ways and Means Committee from the Budget Committee because he said he wanted even greater influence on national fiscal policy, and his prescriptions are anathema to most Democrats.

But the current flak following Mr. Ryan stems from a growing and powerful collection of far-right pundits and news media — from Mark Levin to Laura Ingraham to the sites RedState and Breitbart and the new Conservative Review — that have successfully wielded influence over Republican voters and lawmakers in strongly conservative districts.

Their bill of particulars against Mr. Ryan have shifted from the national debt and spending to immigration. Lately, they have focused on Mr. Ryan’s enthusiastic support for free trade, traditionally a policy that has gotten broad Republican support but is now being used as a bat against him. Beyond Mr. Ryan, the conservative targets have seemingly shifted from old time establishment lawmakers to a process seemingly more akin to random selection.

On Monday, a Tea Party group in Alabama sent out warning flares to Representative Martha Roby, a Republican, advising her that she would come under fire if she supported Mr. Ryan for speaker.