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WEST MONROE, Louisiana - At a campaign stop at a firing range, while Rick Santorum was firing off some rounds, a woman shouted, "pretend it's Obama."

Santorum, who was far from the woman, couldn't hear the comment as he proceeded with his target practice. Neither could his staffers.

But the yell - the identity of the yeller is not clear, although the words were clearly audible - was in close proximity to journalists traveling with the candidate.

"It's absurd," Santorum said of the woman's outburst when reporters told him about it. "No we're not pretending it's anybody but shooting pistols. It's a very terrible and horrible remark and I'm glad I didn't hear it."

Santorum is expected to easily win the Louisiana primary on Saturday, but his chances of wresting front runner status from Mitt Romney have dwindled as Romney has built a strong delegate lead.

Perhaps sensing Romney's proximity to clinching the nomination,  Santorum has sharpened verbal attacks on the former Massachusetts governor, suggesting he is too moderate for Republican voters and could not beat President Obama.

Santorum sought in a written statement to clarify today that he did not mean he vote against Romney if Romney is the nominee in November.

"I would never vote for Barack Obama over any Republican and to suggest otherwise is preposterous," he wrote. "I was simply making the point that there is a huge enthusiasm gap around Mitt Romney and it's easy to see why - Romney has sided with Obama on healthcare mandates, cap-and-trade, and the Wall Street bailouts.  Voters have to be excited enough to actually go vote, and my campaign's movement to restore freedom is exciting this nation.  If this election is about Obama versus the Obama-Lite candidate, we have a tough time rallying this nation."