WASHINGTON (AP) — Rick Santorum on Sunday attacked rival Mitt Romney calling him “the worst Republican in the country to put up against Barack Obama” even as it appears the former Massachusetts governor is on pace to clinch the Republican party’s nomination.

Santorum told voters that Romney is “uniquely disqualified” to be the Republican’s presidential pick and urged his supporters to stand with him even as he faces an increasingly improbable pathway to the nomination, despite an easy victory in the Louisiana primary the night before.

With all Louisiana precincts reporting, Santorum captured 49 percent of the vote to 27 percent for Romney. Newt Gingrich, was far back at 16 percent, followed by Ron Paul with 6 percent.

Although the victory gives Santorum bragging rights and 10 more delegates, it does not change the overall dynamics of the race. The former Pennsylvania senator still dramatically lags behind Romney, a former Massachusetts governor, in the battle for delegates to the party’s August nominating convention in Tampa, Florida.

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With the state-by-state primary and caucus contests more than half complete, Santorum has won just 27 percent of the delegates. Romney has been accumulating delegates at a 54-percent clip. Most of the remaining states award delegates proportionally based on primary results, making it even more difficult for Santorum to close the gap.

The odds would seem to rule out nomination of Santorum. But as he savored his victory in Louisiana, the ultraconservative vowed to remain in the battle. Santorum was campaigning in Wisconsin, which holds its primary on April 3.

But the Republican establishment is increasingly coalescing around Romney’s candidacy out of concern that an extended nomination fight could hurt the party’s chances against President Barack Obama. The Democratic incumbent faces no serious primary challenge and his re-election campaign already is well under way.

An influential Republican senator said on Sunday that the nominating race was all but finished.

“I think the primary is over. Romney will be the nominee,” South Carolina’s Lindsey Graham told CNN. “The fat lady hasn’t sung yet. But she’s warming up.”

Romney has churned through the nomination contest with a huge financial and organizational advantage, further dimming the likelihood that Santorum will pull off the nearly impossible task.

Romney remains far ahead with 568 delegates to Santorum’s 273, according to an Associated Press tally. Newt Gingrich follows with 135 and Ron Paul has 50.

Romney is just short of half the 1,144 delegates it will take to clinch the nomination ahead of the convention this summer in Tampa, Florida, while Santorum is shy of accumulating a quarter of the needed delegates. His organizational disadvantage will show again in the District of Columbia primary, also on April 3, where Santorum failed to get on the ballot.

Copyright 2012 The Associated Press.