Story highlights Rep. Bill Cassidy, a Republican, won Louisiana's runoff Saturday night

He becomes the ninth GOP pickup in the Senate this election cycle

Incumbent Democrat Sen. Mary Landrieu campaigned through Saturday

Democratic Sen. Mary Landrieu lost her Senate runoff race Saturday night, felled by the red tide that's swept the South and ties to an unpopular President that she couldn't shake.

CNN called the race for her Republican opponent Rep. Bill Cassidy a little over a half hour after the polls closed. Republicans picked up nine Senate seats this election cycle and will have control of 54 seats in the chamber next year.

Once seen as Democrats' strongest incumbent, Landrieu ended up such a long-shot in her runoff with Cassidy that the Democratic Senatorial Campaign Committee cut its investment in the state, a move that Landrieu decried as leaving "a soldier on the field."

In her concession speech, Landrieu touted her own "record of courage, honesty and integrity and delivering for the state when it mattered the most."

The senator also said she didn't regret her vote for Obamacare, which the GOP used to attack her and every other vulnerable Democratic senator this cycle.

"This is something to be proud of, and I'm glad we fought for it," she said, touting some of the benefits of the law.

"Shake it Off," Taylor Swift's pop anthem to moving past defeat and ignoring critics, played as Landrieu hugged the staff and family members gathered on the stage.

And tears could be seen throughout the crowd as the event wound down on Saturday night.

An energetic Cassidy, meanwhile, opened his victory speech with a surprised, "whoa!"

He told his supporters his win was the "exclamation point" on the declaration that "we want our country to go in a conservative direction," which was made with the GOP's resounding wins on Nov. 4.

He was introduced at his victory party by GOP Sen. David Vitter, who endorsed the congressman and has been active in the race for him. And Cassidy was joined on stage by his onetime GOP foe in the race, retired Air Force colonel Rob Maness, who ran as a conservative alternative to him during the first round of voting but endorsed him in the runoff.

Landrieu ran hard through the very end, insisting even Saturday morning, outside the school where she cast her ballot, that there was still a shot.

Landrieu, any Democrat in Louisiana will remind you, had pulled off stunning upsets before. And a late-breaking controversy surrounding Cassidy's part-time work for Louisiana State University gave Democrats some hope that they could damage him in the final moments of the race.

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But the controversy came too late to pick up much traction, despite Landrieu hammering him at campaign stops throughout the week on it.

Landrieu's campaign pitch centered around her clout in the Senate, and what she can do for the state in Washington. But that argument lost much of its potency on Nov. 4, when Democrats lost the Senate and Landrieu could no longer tout a committee chairmanship.

And Landrieu was never able to effectively localize the race and distance herself from the president, while Republicans tied her to him at every opportunity.

Indeed, even Landrieu's supporters seemed to know it was over before Election Night.

Andrea Neighbours, a supporter at the party, was visibly disappointed when told the race had been called for Cassidy.

But she admitted: "Well, it was coming."

And Cassidy ran a largely error-free, if exceptionally safe, campaign. He held infrequent campaign stops during the runoff and stayed entirely out of the state for the final week of the runoff, returning only for a Monday debate and two rallies Friday.

On Saturday, he was taking a professional development course at the hospital where he works.

But a troupe of volunteers were out Saturday across the state canvassing for him. An army of GOP operatives descended on the runoff, many of whom came to the state after finishing top races elsewhere in the nation.

The Republican National Committee had around 300 staffers in the state and used the runoff period as a testing ground for field and data methods.

And GOP groups supporting Cassidy bombarded Landrieu with millions in attack ads, while a handful of small Democratic groups spent less than half a million for her in the runoff.

Republicans wanted, they said, to put an "exclamation mark" on their wins on Nov. 4.

Even Landrieu's deep familiarity with the state and family name couldn't save her. Moon Landrieu, the senator's father, is a popular former mayor of New Orleans, and Mitch, her brother, is the city's current mayor.

Landrieu canvassed the neighborhood surrounding her father's home on Satuday, much of which is home to low-income and African American residents. She stopped at 66-year-old Aida Gray's house, just a few blocks away from her family's, to shake hands and ask if she would be heading to the polls.

Gray later said that of course she would, because she had known the senator for decades.

"She's a good person, and she'd make a better senator than Cassidy," she said.

But despite her belief that Landrieu was the best candidate for the job, Gray acknowledged the odds were stacked against the senator.

"It's in God's hands now," she said.