Sens. John McCain (R-Ariz.) and Hillary Rodham Clinton (D-N.Y.) inched closer to securing their respective parties’ presidential nominations Saturday with victories in key contests. McCain was declared the winner of the South Carolina GOP primary Saturday evening, edging out former Arkansas Gov. Mike Huckabee. Former Sen. Fred Thompson (Tenn.) and former Massachusetts Gov. Mitt Romney were vying for third place. Earlier in the day, Clinton defeated Sen. Barack Obama (Ill.) in the Nevada Democratic caucus — a contest that both candidates were hoping to win — 51 percent to 45 percent. Former Sen. John Edwards (N.C.) was a distant third. Republicans also held a caucus in Nevada, though it was sparsely attended and not heavily contested. Romney won that vote easily. For Democrats, the next key election is the South Carolina primary on Jan. 26. A poll earlier this week showed Obama with a 9-point lead, and it will be interesting to see whether Clinton gets any bounce from her Nevada victory. For Republicans, the next critical contest is the Florida primary on Jan. 29. McCain, Huckabee and Romney are all hoping to do well there, and it will be the first real test for former New York Mayor Rudy Giuliani’s unconventional White House bid. The nomination fights are certain to continue until at least Feb. 5, when 22 states are scheduled to hold primaries or caucuses. — Josh Kurtz