Democrats have insisted that they will push to win the only outstanding Senate race in the country — a Dec. 10 runoff election in Louisiana — but it appears to be trending toward the Republican candidate, which would give the party an effective 52-48 majority next year.
State Treasurer John N. Kennedy won the most votes on Nov. 8, but in a crowded field he fell far short of the 50 percent threshold needed to win outright.
Foster Campbell, a Democrat and member of the Louisiana Public Service Commission, placed second, setting up a showdown that Democrats hoped could pare the Senate Republican majority to just a single seat.
The latest polling, though, shows Mr. Kennedy with a massive advantage, and he appears eager to nurse his lead and ride the aftershocks of the surprise wave that powered Republican Donald Trump to the presidency.
Mr. Campbell says Mr. Kennedy is ducking the voters and that his campaign is banking on his independent streak to pull off an upset in a state that Mr. Trump carried by nearly 400,000 votes over Democrat Hillary Clinton.