Santorum fights back against critics with barbs AIKEN, S.C. (AP) - Searching for traction, Rick Santorum is on the attack these days - against everyone, it seems. On Tuesday alone, the Republican presidential candidate branded Mitt Romney a liberal, said Newt Gingrich's policy positions have been "all over the place" and laughed that Ron Paul has been running for president "since 1938." The more acerbic tone comes as the South Carolina primary looms on Saturday and with polls showing Santorum trailing Romney, the front-runner, and other rivals. In the effort to claw his way to the front of the pack, Santorum coupled his scathing critiques of his rivals on the campaign trail with a new TV ad that compares Romney to President Barack Obama. Obama supported the Wall Street bailouts. So did Romney. Obama gave us radical Obamacare that was based on Romneycare," the ad's narrator says. Obama's a liberal on social issues. Romney once bragged he's even more liberal than Ted Kennedy on social issues. The ad then asks: "Why would we ever vote for someone who is just like Obama?" Santorum urged South Carolina conservatives to coalesce around one of their own or face Romney as the GOP nominee. "He's got a lot of money, but he doesn't have the convictions, the authenticity nor the record that is necessary to win this election," Santorum told voters. Please consolidate. At the same time, he said Gingrich wasn't the best conservative option. "Newt is bold, but he is all over the place," Santorum continued. Attacking capitalism, supporting capitalism. Against global warming, for global warming. We need someone who is bold and consistent. Santorum, often sarcastic as a campaigner, offered this explanation for how Paul, 76, had bested him in the nation's first primary: "Congressman Paul had been running in New Hampshire for president since 1938." Conservatives appeared to be recognizing their dilemma: Texas Gov. Rick Perry, Gingrich and Santorum all were vying to emerge as the leading alternative to Romney but were fracturing their support. "We conservatives are splitting the vote," Aiken voter Michele Merritt told Santorum. Is there not anything that those conservatives can do to get together for the good of the country and try to coalesce behind one person that will be able to take on Romney and win? Because I really, really don't want Romney to get the nomination. Santorum nodded but stopped short of urging anyone to exit from the race. "I believe everybody has a right to be in this race if they want to be in this race and fight as hard as they want for as long as they want," he later told reporters in Lexington. I'm not into political games, or political deals. Santorum finished a close second in Iowa on a shoestring budget. Fundraising took off after that and he was finally in a position to spend some of the $3 million he raised that week. Romney's allies, meanwhile, were airing an ad that says Santorum "even voted to let convicted felons vote." Santorum complained that the TV spot, while referring to "felons," shows someone in an orange prison jumpsuit, suggesting that Santorum would allow them to vote while still incarcerated. Santorum has supported voting rights only for those who have served their sentences and been released. He called the ad "one of the cheapest shots ever" and said Romney should tell his allies to back off. "I would never, ever, ever want to be affiliated or associated with anybody doing something for me that I know is blatantly false," Santorum said. Romney countered that "people who have been released from prison are still called felons if they've committed felonies." Associated Press writers Kasie Hunt and Thomas Beaumont contributed to this report.