The emerging consensus is that Rick Santorum is the biggest threat yet to Mitt Romney. They have similar strengths, like a nice family and victories in blue states, notes Ramesh Ponnuru at Bloomberg View, but Romney has many of Santorum's weaknesses, only weaker. How can Romney portray Santorum as a fan of big government when he created the template for Obamacare? It appears voters increasingly find this argument persuasive. Here's our guide to today's polls and which ones matter.
Findings: Santorum is slightly ahead of Romney nationally, with 30 percent to 27 percent, respectively.
Pollster: CBS News/ New York Times
Methodology: Interviews with 1,064 registered voters who said they'd vote in the Republican primary from February 8 to February 13.
Why it matters: On Monday, two polls showed Santorum and Romney tied; a third one with Santorum surging shows it's not a fluke. On January 20, Santorum had just 16 percent of the national vote, while Romney had only a teeny bit more than he does now, 28 percent.
Caveat: In this race, the Not Romney leaders haven't lasted very long. Newt Gingrich's support has been cut in half since just before the South Carolina primary.