President Trump slammed the Obama administration Monday for failing to investigate Russia meddling while it was happening.

“Why did the Obama Administration start an investigation into the Trump Campaign (with zero proof of wrongdoing) long before the Election in November? Wanted to discredit so Crooked H would win. Unprecedented. Bigger than Watergate! Plus, Obama did NOTHING about Russian meddling,” Mr. Trump tweeted.

Why did the Obama Administration start an investigation into the Trump Campaign (with zero proof of wrongdoing) long before the Election in November? Wanted to discredit so Crooked H would win. Unprecedented. Bigger than Watergate! Plus, Obama did NOTHING about Russian meddling. — Donald J. Trump (@realDonaldTrump) March 5, 2018

Special counsel Robert Mueller is investigating the Trump campaign for possible collusion with Russia in the 2016 election. Mr. Trump, as well as several of his former campaign and current White House aides, have denied any collusion.

Former Vice President Joe Biden said the Obama administration hesitated to sound the alarm for fear of becoming involved in the election.

“The bottom line was it was tricky as hell. It’s easy to say now, well maybe we should have said more,” Mr. Biden said at a Council on Foreign Relations event in January.