Singer Loomis Butchers National Anthem at Live Event, Begs for Do-Over

Step aside, Fergie ... up-and-coming singer Loomis is the latest person to totally butcher the National Anthem, and the flub is super toe-curling, to say the least.

As you can see, the singer starts off strong at the Free and Equal Elections Presidential Debate on Thursday ... but quickly goes off-key, losing her cool and begging into the mic, "I f***ed it up, I f***ed it up. Can I go back, can I go back please?"

As if that weren't enough, a cameraman chimes in to let her know she’s live -- and she’s horrified, trying to soldier on ... but her cracking voice gets worse.

She’s clearly mortified, admitting mid-song, "I got too nervous!"

Meanwhile, everyone behind her is doing their best to keep a straight face, offering a pitying round of applause when she finally wraps it up.

However, she didn’t get the same sympathetic treatment online, facing a wave of backlash and ridicule on social media.

The event was held for third-party presidential candidates, including Jill Stein of the Green Party ... Chase Oliver of the Libertarian Party ... and Randall Terry of the Constitution Party.