WASHINGTON -- It’s a time-tested move for Republican presidential candidates: Run to the right during the primaries to secure the party’s nomination, then move toward the center to win the White House in November.

The political dance, first choreographed in 1968 by Richard Nixon, could be a delicate one for Republican presidential candidate Mitt Romney.

Perhaps no Republican nominee in recent times has run as hard – or as far – to the right as Romney. Coming from liberal Massachusetts, the former governor had to distance himself from a record that included support for abortion rights, gay rights, and a state health care law that mandates people buy insurance, the essence of the national law that conservative Republicans loathe. He leaned hard right to outflank and dispatch a field of primary challengers that aggressively attacked his conservative credentials and to convince wary conservative voters that he’s truly one of them.

Now as he heads to the Republican National Convention to launch his fall campaign, Romney faces the challenge of battling President Barack Obama for the small sliver of independent moderates who could decide the election’s outcome – without alienating a conservative base that’s still suspicious of his political core.

The recent brouhaha over abortion and rape underscored the test of appealing to both audiences. Romney condemned Republican Missouri Senate candidate Todd Akin’s comment that women cannot get pregnant in cases of “legitimate” rape, reasserted his support for abortion rights in cases of rape, but also stressed his opposition to abortion in most cases.

“Romney has to attract a majority of independent voters in the middle in order to win,” said Mark McKinnon, who advised George W. Bush’s presidential campaigns. “He can’t win simply by motivating GOP base voters.”

Romney’s task is “keep the base, but you’ve also got to get the Washington, D.C., suburbs in Virginia, the (Florida) I-4 Corridor, and the Philadelphia suburbs,” places where independent and undecided swing voters dwell, said G. Terry Madonna, director of the Center for Politics & Public Affairs at Pennsylvania’s Franklin & Marshall College.

“There’s no clear-cut path for him that’s not without drawbacks,” Madonna said.

Romney’s path to the nomination veered sharply to the right during primary season. Even before picking Rep. Paul Ryan of Wisconsin as his running mate, Romney embraced the House Budget Committee chairman’s budget plan, which revamps Medicare by giving retirees payments to buy health insurance coverage; talked tough on illegal immigration and opposed the DREAM Act, which would allow young people who came to the U.S. illegally as children to stay here if they’re enrolled in college or serve in the military; and staunchly opposed legalized abortion and federal funding for Planned Parenthood.

The stances helped Romney outflank his opponents, but they may not appeal to independents and undecided swing voters who tend to be less “ideological and more moderate,” according to Andrew Kohut, president of the Pew Research Center.

Making things potentially even more complicated for Romney this fall is that for the first time in four election cycles independent voters have unfavorable opinions of both parties – the Republican Party more so.