Donald Trump took to Twitter Friday to insist that despite months of investigating, no proof has emerged that he colluded with Russia to tilt the 2016 presidential election in his favor.

"After 7 months of investigations & committee hearings about my 'collusion with the Russians,' nobody has been able to show any proof. Sad!" the US president tweeted.

Trump's young presidency has been battered by allegations -- under investigation both by Congress and the FBI -- that Russia interfered to sway the November election in his favor.

The president has long vehemently denied any collusion with Moscow.

In a second tweet, Trump touted his "powerful" presence on social media, despite widespread criticism that his recurring rants on Twitter and other online media have only compounded his legal and political problems.

"The Fake News Media hates when I use what has turned out to be my very powerful Social Media -- over 100 million people! I can go around them."

On Thursday, Trump blasted news reports that he is under criminal investigation as a "witch hunt" against him led by some "very bad" people.

"You are witnessing the single greatest WITCH HUNT in American political history -- led by some very bad and conflicted people!" he said in an early morning tweet.

The president did not directly address allegations that he is being probed for possibly obstructing justice -- a potentially impeachable offense.

The FBI probe, now in the hands of special counsel Robert Mueller, reportedly shifted its focus to allegations of obstruction in the days after Trump fired the agency's then-director James Comey on May 9.

The new allegations against Trump center on his own admission that he fired Comey because of the Russia investigation, and suggestions he asked several top intelligence officials for their help altering the inquiry's direction.