The Republican Party wasn’t always a conservative party.  Waves of conservative insurgency and resurgency during the past 50 years have transformed the Grand Old Party into the only major party with a core constituency that desires individual freedom and limited government.

The emergence of TEA (for “taxed enough already”) parties and the 912 Project — often referred to jointly as the Liberty Movement — is the newest chapter in this resurgence.

In 1964, conservatives, backing Barry Goldwater, wrested the presidential nomination from the Eastern moderate-liberal establishment, which backed Nelson Rockefeller.  Although Goldwater was trounced by Lyndon Johnson in the general election, his candidacy sewed the seeds of the “Reagan revolution” in 1980.

In the meantime, Republicans twice nominated Richard Nixon who, although conservative on national defense, also engaged in Keynesian “stimulus” spending, presided over vast expansions of the regulatory bureaucracy, and even sought to impose wage and price controls.

When Ronald Reagan defeated George H. W. Bush for the 1980 presidential nomination, Bush and old-line Republicans scoffed at Reagan’s proposal to revive the economy with tax cuts, deriding the plan as “voodoo economics.”  Thirty years later, no serious Republican candidate would dare deny that higher taxes harm the economy.

Even after Reagan, the intra-party ideological struggle continued.  When Americans revolted against the first two years of Bill Clinton’s presidency, Newt Gingrich became the top-ranked Republican in Congress, replacing previous Republican leader Robert Michel, a milquetoast who seemed averse to playing hardball with Democrats.  Gingrich’s history of tangling with the GOP’s old bulls included his jibe that Sen. Bob Dole was “the tax collector for the welfare state.”

But conservatives have human frailties, too, and Gingrich, after being out-maneuvered by Clinton during the 1995 federal government shutdown, seemed thereafter to focus more on retaining power than advancing a conservative agenda, writes Sen. Tom Coburn in Breech of Trust.  When Republicans lost seats in 1998, Gingrich resigned.

When George W. Bush was elected in 2000, backed by the narrowest of majorities on Capitol Hill, Republicans walked on eggshells. The Sept. 11 attacks provided them with a purpose but pushed fiscal responsibility and limited government into the background.

The quest for re-election and Karl Rove’s political – thought not necessarily conservative – acumen helped Republicans win big in 2002 and 2004.  But the party forfeited its identity as a force for fiscal responsibility and limited government, leading to electoral disasters in 2006 and 2008.  Those thrashings reminded most Republican survivors that principles are more important than parties in the minds of swing voters who decide elections.

The arrogance and relentless big-government crusades of Barack Obama, Nancy Pelosi and Harry Reid were like a cold shower to Republicans and to many Americans, providing a new opportunity to draw a sharp contrast between the two parties.

Nevertheless, much of the surviving Republican establishment failed to account for the tidal shift in voter attitudes.  Just as voters soured on Republicans in 2006 – merely two years after handing them their largest majorities in half-a-century – they are now fed up with Democrats, who thought 18 months ago that their majorities would last for a decade.

Inside-the-beltway Republicans aimed to increase their numbers by recycling well-known candidates who appeared to be safe bets to win in November.  Some of those safe bets, however, were too reminiscent of the “go along to get along” crowd that voters rejected in the previous two elections.

By ousting Mike Castle in Delaware, Charlie Crist in Florida, and Lisa Murkowski in Alaska, the new conservative resurgency humbled politicians who erroneously believed themselves irreplaceable.  Those are Republicans who, although perhaps more likely to win in November, would further frustrate voters who expect Republicans to stand for basic conservative principles, like low tax rates, balanced budgets and limited government.

Not all TEA party favorites will win in November, but many will turn out to be exactly the counter-balance to Barack Obama that voters want so badly.

If 2010 isn’t the year for conservative candidates to break new ground, then such a year will never come.