A poll worker lifts the curtain as Sen. Kelly Ayotte, R-N.H., center, leaves the voting booth with her daughter, Kate, Tuesday, Nov. 8, 2016, at Charlotte Avenue Elementary School in Nashua, N.H. (AP Photo/Elise Amendola)
A poll worker lifts the curtain as Sen. Kelly Ayotte, R-N.H., center, leaves the voting booth with her daughter, Kate, Tuesday, Nov. 8, 2016, at Charlotte Avenue Elementary School in Nashua, N.H. (AP Photo/Elise Amendola) Credit: Elise Amendola

WASHINGTON — Democratic chances of retaking the Senate are slipping away. They would have to take all the remaining critical contests in Missouri, Nevada, New Hampshire, Pennsylvania and Wisconsin. Democrats grabbed a Republican-held seat in Illinois on Tuesday as they fought to retake control of the Senate from the GOP. But Republicans held onto seats in Indiana and Florida, and several other key races were too close to call.

In Illinois, GOP Sen. Mark Kirk had long been considered the most endangered Republican incumbent, as he faced a strong challenger in a state that favors Democrats in presidential election years. His opponent, Democratic Rep. Tammy Duckworth, is a double-amputee Iraq war veteran with a compelling personal story.

In Indiana, GOP Rep. Todd Young beat former Democratic senator and governor Evan Bayh, who mounted a much-ballyhooed comeback bid, but wilted under scrutiny.

And in Florida, GOP Sen. Marco Rubio beat Democratic Rep. Patrick Murphy, giving Rubio a platform from which he could mount another bid for president in 2020. The outcome was not unexpected since Murphy had been abandoned by his own party by late in the campaign, but polls had tightened heading into Election Day.

But with several other races too close to call, Senate control depended on outcomes in North Carolina, Missouri, New Hampshire and elsewhere as the night wore on.

The outcomes came as GOP incumbents around the country faced energized Democratic challengers trying to oust them in costly and caustic battles shadowed every step of the way by the polarizing presidential race between Republican Donald Trump and Democrat Hillary Clinton.

In GOP-held North Carolina, Missouri and New Hampshire, it looked like it could go either way as voting progressed. The races were also close in Pennsylvania and Nevada.

Republicans hold a 54-46 majority in the Senate, including two independent senators who caucus with the Democrats.