Republicans are gaining significant ground in the fight over federal spending, but a dispute has been simmering within the GOP's ranks over just how aggressively to confront the White House and the Democratic Senate.

As one might expect, the tea partiers are clamoring for confrontation, while Speaker John Boehner and GOP leaders continue pressing ahead toward the campaign goal to cut $100 billion.

House Republicans have passed two stopgap measures that achieve that level of cutting on a temporary basis. In lieu of bipartisan agreement on a longer-term spending plan, a two-week stopgap funding bill passed March 1 cut $4 billion from last year's spending levels. A three-week extension, passed on Tuesday, cut $6 billion. Multiply those cuts out over an entire year, and House Republicans hit their $100 billion mark.

But conservatives in the party have grown impatient, and if the pressure on GOP leaders isn't intensifying, it's at least been sustained. Unity is turning into dissent.

Republicans were almost completely united in passing $60 billion in cuts on Feb. 19 (only three voted against it), though the plan was destined to be rejected by Senate Democrats. On March 1, only six Republicans broke ranks to vote against the first temporary measure. But on Tuesday, 54 sided against leadership and opposed the current three-week extension. By the numbers, Boehner and Republican leaders actually needed Democratic votes to pass it.