The politicians endorsed by Beyonce and Taylor Swift have lost their races in the U.S. midterm elections.

Beyonce went public with her support of Beto O'Rourke on Tuesday (06Nov18), backing the Texas Congressman in his run for Senate by rocking his campaign merchandise online.

Alongside two pictures of herself in a 'Beto for Senate' cap, the mother-of-three encouraged her fans to vote, concluding her message by writing: "Every vote counts. Every race matters. Everywhere."

However, even Beyonce's backing wasn't enough to help O'Rourke take the Senate seat, as he was beaten by Republican candidate Ted Cruz.

Following his loss, actress Alyssa Milano took to Twitter to pledge her support for O'Rourke to run against U.S. President Donald Trump in the 2020 election, writing: "Beto lost? That’s ok. Now he can run for President. #Beto2020."

Olivia Wilde, Busy Philipps and Josh Gad also voiced their support for an O'Rourke presidential run in 2020.

Meanwhile, Phil Bredesen, who had been endorsed by Shake It Off singer Taylor, lost his race to become the next Tennessee governor, with Republican candidate Marsha Blackburn instead becoming the state's first woman governor.

In a post in October explaining why she was backing Bredesen for the seat, Taylor told fans that Blackburn's voting record, which has seen her vote against equal pay for women and anti-LGBT legislation among other things, meant she couldn't support her bid for the governor position.

"I cannot vote for someone who will not be willing to fight for dignity for ALL Americans, no matter their skin colour, gender or who they love," Taylor said at the time. "Running for Senate in the state of Tennessee is a woman named Marsha Blackburn. As much as I have in the past and would like to continue voting for women in office, I cannot support Marsha Blackburn. Her voting record in Congress appalls and terrifies me."

Taylor's endorsement of Bredesen saw a voter registration boost, with 65,000 people registering to vote in the 24 hours after the singer's social media post.