No candidate will sweep all 10 contests — which feature in some cases complicated delegate rules and span politically diverse regions from Alaska to Vermont to Oklahoma.
But a Santorum victory in Ohio or broader success elsewhere will likely ensure his place as Romney's top rival. And that would help ensure that the contraception debate and other social issues play prominently in the Republican presidential contest going forward. Santorum has made headlines in recent days by emphasizing the need for two-parent families and fewer pregnancies out of wedlock. Saturday night, Santorum told an Ohio audience that the nation's inattention to conservative social values is "damning people."
In Oklahoma City on Sunday, Santorum was greeted by protesters who shouted slogans like "Get your hate out of my state." As Santorum supporters chanted "We pick Rick," the candidate himself was barely audible.
Earlier, he dodged the Limbaugh controversy. "That's not my business," he said when asked Sunday about Limbaugh's apology.
Romney has avoided the issue in recent days as well, saying only that Limbaugh's comments about the college student were "not the language I would have used, but I'm focusing on the issues that I think are significant in the country today, and that's why I'm here talking about jobs in Ohio."
Asked whether Romney's comments went far enough, Fehrnstrom said: "There's extreme rhetoric on both sides of the political spectrum. I think the political process is best served if everybody tones it down, not only those on the right but also intolerant voices on the left."
Gingrich told CNN's "State of the Union" that he's glad the conservative commentator issued the apology on Saturday and that it's time to move beyond the controversy. He said it's "silly" to suggest that Limbaugh speaks for the GOP.
Republican observers suggest that any continued focus on social issues could hurt the party.
GOP strategist Phil Musser said the contraception debate "has been distracting and has sucked up too much political oxygen."
"While this is an important issue that illustrates the overreach of Obamacare, it's nowhere near the top of what most Americans are most focused on right now," he said, describing it as a "short-term challenge."
Santorum's focus on social issues has helped fuel his success in lower-turnout elections, where tea party activists and evangelical voters generally play a more active role. Lingering skepticism about Romney's conservative credentials from those voters has allowed Santorum and Gingrich to stay in the race, despite Romney's advantages.
The Super Tuesday contests and beyond are about math almost as much as political symbolism.
No candidate can technically claim his party's nomination before collecting 1,144 delegates, although history suggests a nominee usually emerges much earlier once weaker candidates lose the ability to raise money.
Romney holds a commanding delegate lead, including Saturday's Washington results, according to Associated Press projections.
He won 30 delegates in Washington while Paul and Santorum each won five, bringing Romney's total to 203, compared to 92 for Santorum, 33 for Gingrich and 25 for Paul.
There are 419 delegates at stake Super Tuesday. Also, Wyoming Republicans will hold county conventions from March 6 through March 10, with 12 delegates to the party's national convention up for grabs.
Associated Press writer Katie Fretland in Oklahoma City contributed to this report.
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