It was yet another embarrassing spectacle of Republicans squabbling over who was for big government first. Jim Talent, a former senator from Missouri acting as a surrogate for Mitt Romney, took Rick Santorum to task for voting for Medicare Part D while in the Senate in 2003.

Medicare Part D was indeed an egregious example of federal government growth. It added at least $7 trillion to the already substantial unfunded liabilities of the Medicare system. The deficit-financed prescription drug benefit was also the biggest new entitlement program since the Great Society. On a media conference call, Talent described it as a “big expansion of a federal entitlement.”

According to reporters who were on the call, Talent went so far as to say Santorum’s Medicare Part D vote placed him in the “liberal wing of the Republican Party” on fiscal issues. There was just one problem: Talent also voted for Medicare Part D. Talent later told the Weekly Standard‘s Michael Warren that the senators’ Bush-era Medicare votes could “be explained or justified” and that Romneycare was “on balance, a conservative measure” that had the Heritage Foundation’s backing at the time.

The moral of this story: Republicans generally do a very good job of promoting fiscal conservatism when the Democrats are in power. Yet when they control the White House and Congress, Republicans have a tendency to lose their way. They are the party of the Paul Ryan budget under Barack Obama but the party of Medicare Part D, No Child Left Behind, and Romneycare under GOP chief executives.

Whatever happens in the presidential election, someone will need to resist big spending whether it comes from liberal Democrats or leap-year conservatives. One candidate who recognizes this need is Ted Cruz, who is running for the Republican nomination to replace retiring Sen. Kay Bailey Hutchison in Texas. Cruz told this writer that having the right party label isn’t good enough.

“Texas is too Republican a state to settle for anything less than a conservative leader,” Cruz says. Even casting the right votes and getting high ratings from conservative groups isn’t as important as rocking the boat. Cruz argues that the solution is electing a critical mass of committed constitutional conservatives.

Cruz identifies Jim DeMint, Rand Paul, and Mike Lee as examples of what he is talking about (he notes that all three senators have endorsed him in his primary). He also points to Marco Rubio and Pat Toomey, suggesting that the generation of conservatives who came of age in the Reagan years are ready to make their mark on the party.

When Cruz first jumped into the race for Senate, admirers immediately predicted an epic Tea Party against the GOP establishment battle like Rubio versus Charlie Crist in Florida or Paul versus Trey Grayson in Kentucky. But for a while, the conservative vote was splintered among several candidates (the most important competitor on the right was Michael Williams) and Lt. Gov. David Dewhurt seemed like a strong frontrunner.

Gradually, Cruz consolidated conservative support. He has the backing of FreedomWorks, the Club for Growth, Redstate.com’s Erick Erickson, and the radio talk show host Mark Levin. George Will, the dean of Washington conservative columnists, opined that for “conservatives seeking reinforcements for Washington’s too-limited number of limited-government constitutionalists, it can hardly get better than” Cruz.

A graduate of Princeton and Harvard Law (magna cum laude), Cruz displays legal interests quite uncharacteristic of the Ivy League: he believes it is important to limit the federal government to its constitutionally enumerated powers, as the Ninth and Tenth Amendments make clear. The former Texas solicitor general has tried to put these principles into action.

Cruz understands that fighting for limited government will sometimes entail fighting other Republicans. He has assailed Dewhurst’s proposal for a Texas wage tax on businesses as a thinly veiled personal income tax. He’s under no illusion that Americans are likely to elect 51 constitutionalist senators, but says a dozen or so working within the Republican caucus could do a world of good.

The ideological composition of the Senate Republican conference will be determined by primary races in states like Texas, Indiana, and Utah. But in some segments of the party, there has been movement away from the idea that individual mandates and deficit-funded government programs are only bad when instituted by Democrats.

Looking at the GOP presidential candidates and their surrogates, many conservatives undoubtedly feel such a changing of the guard couldn’t come too soon.