The end of the Republican presidential contest was looming as Mitt Romney and Rick Santorum headed for campaign stops Wednesday in Pennsylvania.

A Romney victory on April 24 could be the culmination of a long and contentious primary war. Losing his home state would likely force Santorum to abandon an increasingly uphill attempt to carry the conflict all the way to the national convention in August.

With a triple-primary sweep on Tuesday, Romney advanced more than halfway to the 1,144 delegates he needs to secure the nomination. But polls show that Republican voters are in no hurry for the race to be over, and Santorum isn’t giving up.

The most recent statewide polling gives Santorum and his supporters hope that the race will go on past Pennsylvania. A Quinnipiac University survey completed Sunday showed the former senator with a 6 percentage point lead over Romney. Santorum hit the home-state theme repeatedly Tuesday night.

“You know me” was Santorum’s refrain in remarks to a lackluster crowd of perhaps 250 supporters in suburban Pittsburgh, where his career in politics began more than two decades ago.

Over the next three weeks, the GOP contenders are expected to campaign aggressively across this state, which resembles other places where Romney has prevailed. The Republican primary electorate has more of the moderate voters who lean Romney’s way and relatively fewer of the evangelical Christians who continue to resist him. Much of the Republican establishment is either staying neutral or is on his side, despite -- or, in some cases, because of -- past association with Santorum.

Romney will employ the same hard-edged tactics that he used to overtake Santorum in Michigan, Ohio, Illinois and Wisconsin: an unwavering negative ad assault over earmarked spending, Senate votes to raise the national debt and allegations that two decades in the nation’s capital had transformed Santorum into a creature of Washington.

Already, according to Pennsylvania politicians, automated calls from the Romney campaign are going out across the commonwealth, reminding voters of some history that Santorum would like them to forget (his 2004 primary endorsement of Senate moderate Arlen Specter over a popular conservative challenger). If past is prologue, it is only be a matter of time before superior financial resources and that flood of attack ads turn public opinion Romney’s way.

But Santorum’s remarks on Tuesday night were both a warning and a reminder that Romney’s formula is untested on Santorum’s home turf. Last month, Newt Gingrich withstood the Romney assault in his adopted home state of Georgia -- by campaigning as if he were seeking statewide office, rather than the presidency. The former House speaker largely ignored other states holding primaries the same day, a template Santorum is likely to follow (Romney is a heavy favorite in four other eastern primaries on April 24: New York, Connecticut, Rhode Island and Delaware).

Santorum has acknowledged that Pennsylvania is must-win for him. A defeat would effectively destroy his credibility as a presidential contender. But a victory could carry him to the final primaries in June, particularly because, as he alluded to Tuesday night, the May primaries are in states more favorable to a conservative candidate.

For Romney, knocking Santorum from contention with a Pennsylvania win would shorten the primary season by up to two months (in theory, by even more than that, if Santorum, Gingrich and Ron Paul were otherwise able to make a case that Romney hadn’t secured a delegate majority ahead of the nominating convention).

With the primary phase behind him, Romney would be able to devote his energies to uniting Republicans and erasing sour memories of a rough intra-party struggle. He could raise money in earnest for the general election and focus more intently on challenging a vulnerable incumbent president.

After his latest primary wins, those tasks are high on Romney’s must-do list. But the top item is, still, disposing of the Santorum threat. Until he does that, he can’t really claim the nomination.

paul.west@latimes.com