Trying to convince slash-the-government Republicans on Capitol Hill that tax increases will be necessary to bring down the nation's federal debt is a thankless job. So is convincing them it's in their political interest to help President Barack Obama and the Democrats raise the $14.3 trillion debt ceiling. That makes Senator Tom Coburn of Oklahoma and Representative Kevin McCarthy of California the Republicans' odd men out.

As a summer deadline to increase the federal borrowing limit approaches, McCarthy is warning his colleagues that inaction is not a viable option. It's a tough pitch at a time when Republican leaders, maneuvering for advantage in the debt debate, say they'll allow the nation to default unless the deal includes steep spending cuts and no tax increases.

Coburn, a blunt obstetrician-turned-senator known as "Dr. No" for his tough talk about the budget, is preaching an equally unpopular message to fellow Republicans. He's less concerned about the short-term debt ceiling debate than the country's long-term debt burden. If lawmakers from both parties are serious about averting a debt crisis, he says, they must accept a combination of spending cuts and tax hikes (though Coburn prefers the more palatable "revenue increases").