President Trump has taken to Twitter to troll Mitt Romney, a day after the Republican senator said he was 'sickened' and 'appalled' by what the Mueller Report revealed about the Commander-in-chief's conduct.

On Saturday, Trump tweeted a video compilation of news clips from 2012 which all show Romney - who was that year's Republican Presidential nominee - losing the election to Barack Obama.

The president accompanied the video with a caption reading: 'If @MittRomney spent the same energy fighting Barack Obama as he does fighting Donald Trump, he could have won the race (maybe)!'

Trump's tweet taking aim at Romney quickly amassed tens of thousands of likes

Mitt Romney (left) has been trolled by President Trump (right), with the Commander-in-chief sharing a compilation of clips that show the Republican losing the 2012 Presidential Election to Barack Obama

Trump's tweet quickly amassed more than 24,000 likes, with many of the president's supporters also taking a dig at Romney - who currently serves as the junior senator from Utah.

One labelled him a 'sore loser', whilst another claimed the senator was 'jealous' of Trump's electoral success.

However, the President's tweet also garnered criticism from other followers, who labelled it as 'petty'.

'There is something pitiful and disgusting about a person who has to criticize and belittle others to feel good about themselves,' one wrote.

On Friday, Romney become one of the few Republicans to speak out about the Mueller Report, which was released to the public in redacted form on Thursday.

'I am sickened at the extent and pervasiveness of dishonesty and misdirection by individuals in the highest office of the land, including the president,'he said in a statement.

'I am also appalled that, among other things, fellow citizens working in a campaign for president welcomed help from Russia -- including information that had been illegally obtained, that none of them acted to inform American law enforcement and that the campaign chairman was actively promoting Russian interests in Ukraine.'

Trump (left) and Romney (right) have long had a fractious relationship - but Romney took things to a new level with his attack on Trump on Friday

While most Republicans declined to comment on the explosive report, Romney chastised the President and senior White House officials

The Mueller Report detailed cooperative but not criminal contact between Trump's 2016 election campaign and Russia that assisted him in his defeat against Democratic rival Hillary Clinton.

The report also detailed numerous acts by the president that supported allegations of obstruction of justice, though Mueller, constrained by Justice Department rules, could not himself recommend charges against Trump.

Trump declared victory and exoneration after the report, and later labeled Mueller's work 'total bulls**t'.

However, the number of Americans who approve of Trump has dropped by 3 percentage points to the lowest level of the year in a new poll.

The survey, conducted Thursday afternoon to Friday morning, is the first to measure the response from the American public after the release of the Mueller Report.

It found that 37 percent of adults in the United States approved of Trump’s performance in office, down from 40 percent in a similar poll conducted on April 15.

The poll further found that 50 percent of Americans agreed that 'Trump or someone from his campaign worked with Russia to influence the 2016 election', and 58 percent agreed that the president 'tried to stop investigations into Russian influence on his administration'.

Forty percent said they thought Trump should be impeached, while 42 percent said he should not.