Rick Santorum has withdrawn from the Republican presidential race, effectively wrapping up the nomination for Mitt Romney. Santorum emerged as Romney’s top challenger in the early round of primary contests, but has lost momentum over the past month as Romney built an apparently insurmountable lead. On Tuesday, Santorum conceded defeat.

Rick Santorum: “We made the decision to get in this race at our kitchen table, against all the odds. And we made a decision over the weekend that, while this presidential race for us is over, for me, and we will suspend our campaign effective today, we are not done fighting.”

The remaining Republican presidential candidates are Ron Paul and Newt Gingrich, though both lag even further behind Romney in the delegate count.