GETTYSBURG, PA – One of the hottest-selling t-shirts at souvenir shops outside Gettysburg proclaims, “If at first you don’t secede, try, try again.”

While the pun is popular among Civil War re-enactors at the historic battlefield, the message also has growing appeal in contemporary politics, especially among fractious Republicans.

On both the Right and the Left, activists are convinced that the Republican Party is not pure enough on their issues, and perhaps it is time to break away and create a new political organization to shake up the system.

“It's hopeless; Republicans are as much at fault as Democrats for the debt bomb rocketing towards $20 billion, and we wouldn't be stuck with Obamacare if it weren't for [Chief Justice John] Roberts, a George W. [Bush] appointee,” fumed a conservative congressional staffer at a Fourth of July barbecue in suburban Washington, D.C.

“The Tea Party needs to cut loose from the establishment that's holding back real reform and make a fresh start,” the staffer said.

A similar spirit of independence pervades elephants on the other end of the ideological spectrum. “I think the leadership of the Republican Party is so out of touch with life in America today that I just decided that it's not worth fixing,” explained Jimmy LaSalvia, founder of the gay interest group GOProud, when announcing his split from the Grand Old Party in January. “I don't think they can win a national election again. Pull the plug on the patient, the party's brain dead.”

The problem for those who can't stomach the Democratic Party's across-the-board liberalism is that there is only one other game in town, and that's the GOP.

One doesn’t have to be a party hack to realize that splitting away is politically counterproductive. The history of third parties has not been favorable to the Right.

In 1992, Ross Perot's Reform Party won 18.9 percent of the vote and propelled Bill Clinton into the White House with only 43 percent against incumbent President George H.W. Bush, who lost by 5.6 points.

Again in 1996, Perot's candidacy prevented the opposition to Clinton from unifying, and the Reform Party's 8.4 percent comprised all but a fraction of the margin of victory in an election in which Clinton again failed to reach 50 percent. A one-on-one contest could have ended differently.

Going back further, George Wallace’s American Independent Party received 13.5 percent in 1968, almost costing Richard Nixon the presidency in a tight race against Vice President Hubert Humphrey that Republicans won by less than one point.

Strom Thurmond's States' Rights Party helped re-elect an unpopular Harry Truman in 1948 by convincing southerners and other conservatives not to support moderate GOP nominee Thomas Dewey.

Teddy Roosevelt, the original turncoat Republican, sunk President William Howard Taft’s re-election bid in 1912 by running under the banner of the Progressive Party and splitting the anti-Democrat vote in half.

Woodrow Wilson was elected with only 41.8 percent of the vote that year versus a combined 50.6 percent cut between the warring incumbent and former GOP presidents.

The temptation towards separatism is as old as America. The Pilgrims came to the wilderness to build a new civilization based on freedom that didn’t exist in the old world.

Soon after landing, however, the new community was beset by division as competing factions charged that the others weren’t pure enough and maneuvered to excommunicate the weak links or break off themselves.

John Winthrop, the founding governor of the Massachusetts Bay Colony, spent his career from 1629-1648 fighting the secessionist impulse.

He knew division would weaken the settlers’ ability to repulse attempts to intervene in colonial affairs by the king of England. Only united would the new shining city upon a hill be able to stand.

To keep the experiment in liberty alive, Winthrop made major concessions to rebellious groups he needed to maintain his governing base of support.

Tea Partiers can learn from that lesson: It’s better to reform from within; keep the heat on your leaders and you can force change, but separatism only boosts the forces of tyranny.

Whether favoring fiscal reform, a strong defense or social issues, no conservative constituency is large enough to promote its agenda successfully without partnering with other parts of the center-right coalition.

Today’s Tea Party shouldn’t be focused on self-defeating partisan independence but how to use its muscle to further the conservative cause in the existing two-party system.

Brett M. Decker is consulting director at the White House Writers Group.