Republican Charlie Summers and Democrat Cynthia Dill survived their primaries in Maine on Tuesday, putting them a step closer to replacing outgoing Sen. Olympia J. Snowe, a Republican.
The two winners now must face off against popular former Gov. Angus King, a Democrat-turned-independent, in a general election contest that could determine who controls the upper chamber in Congress next year.
Mr. King appears to be the clear favorite in the race, though it is not entirely clear with whom he would caucus if elected.
In its latest update of the results, the Portland Press Herald reported that Mr. Summers, Maine’s secretary of state, won 30 percent of the vote with the majority of the precincts counted, besting the five other candidates vying for the GOP nod.
Ms. Dill, a state senator, meanwhile, snagged 45 percent of the vote, giving her the victory in the Democratic primary over former Secretary of State Matthew Dunlap.
The most recent poll from the Maine People’s Resource Center, which was released in April, shows Mr. King holding a 34-point lead over Mr. Summers. The poll, though, also suggested that Mr. Dunlap would win the primary.
It also showed that President Obama holds a sizable lead over Mr. Romney in the state.
Citing the increasing polarization on Capitol Hill, Ms. Snowe announced in February that she would not be seeking another term in contest.
The decision sparked applause from some of the more conservative elements of her party who loathed her independent streak, but it also was seen as a blow to the GOP’s hopes of capturing control of the U.S. Senate.