Amy Klobuchar, Pete Buttigieg endorse Joe Biden after dropping out of Democratic presidential race

As clocks in the United States ticked over to Super Tuesday, time ran out for another Democrat seeking the presidential nomination.

Senator Amy Klobuchar ended her bid to become the Democrat's presidential nominee on Monday (local time). Both she and Pete Buttigieg endorsed former Vice President Joe Biden instead, who is emerging as the moderate centrist choice.

They joined Biden at his rally in Texas, one of the 15 states that will vote on Super Tuesday.

"My message to everyone who has been knocked down, counted out, left behind - this is your campaign. We need you, we want you, and there's a place for you in our campaign," Biden said.

Championing the revolution is Senator Bernie Sanders. The only endorsement he wants is from voters this Super Tuesday.

"Let me tell you something - the establishment is getting very, very nervous," Sanders told a crowd at a rally.

And President Donald Trump is talking up a win for Sanders.

"You hear about enthusiasm for crazy Bernie, and that's true he does have some enthusiasm, but much less than we have. Eight months from now we're going to defeat the radical socialist," he says.

Senator Elizabeth Warren is still in the race to be the Democratic nominee, but she's under pressure to join the cull as the race gets real.

If she won't drop out, Sanders wants to win in her home state of Massachusetts instead.

Also fading in the bid to become the Democratic nominee is billionaire Mike Bloomberg, but he says he won't quit however badly he does on Super Tuesday.

He makes $107 million each day, and that money is pumped into advertising to keep his campaign alive.

Success on Super Tuesday requires a big presence on the ground with volunteers, a lot of money fundraised and some serious momentum.

Whether Sanders, Biden or another candidate has the momentum to win on Tuesday, they could take the Democratic nomination and then win the presidency.

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