WASHINGTON — Republicans crushed Democrats' hopes of seizing control of the Senate on Tuesday, winning at least five of eight crucial races that determined the outcome.

Democrats picked up a seat in Illinois and kept the Nevada seat that Sen. Harry Reid held for 30 years. They also still had a chance to win in New Hampshire.

But they fell short of the net gain of five seats they needed to win a majority, or even the four seats they needed to split the Senate 50-50.

Democratic Rep. Tammy Duckworth ousted Republican Sen. Mark Kirk in Illinois. Duckworth, who was first elected to the House in 2012, lost both of her legs in combat in Iraq; Kirk suffered a stroke during his only term in the Senate.

In Nevada, Democratic former attorney general Catherine Cortez Masto defeated Republican Rep. Joe Heck for the open seat created by the Reid's retirement. Reid, the Senate minority leader, campaigned hard for Cortez Masto to succeed him.

In New Hampshire, Republican Sen. Kelly Ayotte and Democratic Gov. Maggie Hassan were running neck and neck.

In Indiana, Republican Rep. Todd Young beat two-term former senator Evan Bayh for an open seat created by the retirement of GOP Sen. Dan Coats. Bayh was a late entrant to the race and had an early lead in polls. And in North Carolina, GOP Sen. Richard Burr, chairman of the Senate Intelligence Committee, defeated Democratic former state representative Deborah Ross.

In Pennsylvania, Sen. Pat Toomey defeated former state environmental chief Katie McGinty. In Missouri, GOP Sen. Roy Blunt was beating Democratic Secretary of State Jason Kander.

But the most unexpected victory for Republicans was in Wisconsin, where GOP Sen. Ron Johnson won a rematch against Democratic former Sen. Russ Feingold, who had led Johnson by double digits in polls just a few weeks ago.

Republicans will now help determine whether the new president can push his or her agenda through Congress for the next two years. If Republican presidential nominee Donald Trump wins, the GOP will hold the executive and legislative branches.

Democrats believed they could wrench the majority away from Republicans because the GOP had so many more seats to defend this year. There were 24 Republican-held seats on state ballots Tuesday and only 10 Democratic-held seats.