WASHINGTON, Aug 12 (Reuters) - Republican presidential

candidate Donald Trump was back on social media platform X ahead

of his interview with billionaire entrepreneur Elon Musk on

Monday in an event that could inject more surprises into the

turbulent U.S. presidential election.

The interview, scheduled for 8 p.m. Eastern Time (0000 GMT

Tuesday), could give the former president an opportunity to

seize the limelight at a time when his campaign is seen as

sagging.

His Democratic rival for the Nov. 5 election, Vice President

Kamala Harris, has erased Trump's lead in opinion polls and

energized Democratic voters with a series of high-energy

rallies.

On Monday morning, Trump returned to X for the first time in

a year, posting a video that highlighted his claim that the four

criminal prosecutions he faces are politically motivated. He

quickly followed with a half-dozen other posts, a potential

indication he will be more active on X going forward.

His last X post before Monday was one in August 2023

appealing for donations and showing a mug shot after he was

booked at an Atlanta jail in relation to felony charges tied to

his attempts to overturn his 2020 election defeat in Georgia.

Trump's access to his account, @realDonaldTrump, was

restored a month into Musk's ownership of X after being

suspended by the platform's previous owners following the Jan.

6, 2021, attack on Congress by his supporters.

Trump frequently posts on his Truth Social platform, which

was launched in February 2022, but his posts there reach a much

smaller audience than on X.

The interview on Musk's social media platform could allow

Trump to reach a different audience than the conservative

faithful who attend his rallies and watch his interviews on Fox

News. However, similar events on the platform have been plagued

by technical problems.

"Am going to do some system scaling tests tonight & tomorrow

in advance of the conversation," Musk wrote on the platform,

formerly known as Twitter.

The interview will be hosted live using Trump's official X

account, his campaign said on Sunday.

Some X users also reported seeing advertisements pop up

supporting Trump. X and the Trump campaign did not immediately

respond to a request for information on whether there had been a

pro-Trump ad buy.

Advertisers have fled X since Musk bought it in 2022. X

earlier this month sued a global advertising alliance and

several major companies, accusing them of unlawfully conspiring

to boycott the site and causing it to lose revenue.

MUSK'S SHIFT RIGHT

Musk could prove to be an unusual interviewer. The world's

richest person backed Democratic President Joe Biden in 2020 but

has tacked rightward since and endorsed the Republican following

the attempted assassination of Trump in July.

Musk, who heads electric car company Tesla, also

started an external super PAC spending group to support Trump's

campaign. The political action committee is now under

investigation in Michigan for possible violations of state laws

on gathering voter information.

Trump, a longstanding critic of electric vehicles, shifted

gears after Musk's endorsement.

"I'm for electric cars. I have to be, because Elon endorsed

me very strongly. So I have no choice," Trump said at an early

August rally.

United Auto Workers President Shawn Fein, campaigning in

support of Harris, called Trump a "sellout."

The Biden administration has worked to popularize electric

vehicles through tax breaks and other support as part of its

broader goal of reducing carbon emissions blamed for climate

change.

Republicans in Congress have opposed those subsidies.

Senator JD Vance, Trump's vice presidential running mate, said

the Biden policy merely subsidizes rich people who purchase the

cars.

Musk has been involved in a swirl of additional

controversies. He has falsely accused Biden and the Democratic

Party of opening U.S. borders to undocumented immigrants in a

ploy to boost the number of potential Democratic voters.

Non-citizens are not allowed to vote in federal elections.

Musk in November 2023 endorsed an antisemitic post on X that

said members of the Jewish community were stoking hatred against

white people. He defended himself, saying the user was speaking

"the actual truth." Musk has also attacked the Anti-Defamation

League, a nonprofit that works to fight antisemitism, accusing

it, without evidence, of being responsible for a drop in

advertising on X.