This indicates how difficult it will be to get any measures through Congress. For example, will the hard-liners sabotage a trade bill that could pass with the support of a majority of Republicans and the Obama White House? Corporate tax reform may be a goner, too.

There are other dangers: The debt ceiling will be reached this spring, and the Highway Trust Fund expires in May. Republicans have a little leverage with the debt ceiling, but not much.

With an eye to the presidential race and tough Senate contests next year, Mr. McConnell and Mr. Boehner know they need some achievements. Given the tone and temper of the first couple months, big stuff may be off the table.

There are, however, some small bites that could pay off politically. More than a few Republicans have railed against corporate welfare or crony capitalism, a message that resonates with an increasingly populist electorate. The test will be whether they can match the rhetoric with action. This isn’t big money; it could be big symbolism.

A good place to start would be the tax break for so-called carried interest, which enables private equity and hedge-fund executives to treat what really is a performance fee as capital gains and thus pay taxes at a lower rate. Critics such as Warren Buffett have suggested this is indefensible. There’s not much money there, but if Republicans could kill a dubious tax loophole, almost all of which goes to the wealthy — and one that Democrats refused to change — it would give real bragging rights.