President Donald Trump on Tuesday ramped up his attacks on special counsel Robert Mueller’s team in a series of tweets, accusing them of meddling with the upcoming midterm election.

On Tuesday, Trump tweeted: The 13 Angry Democrats (plus people who worked 8 years for Obama) working on the rigged Russia Witch Hunt, will be MEDDLING with the mid-term elections, especially now that Republicans (stay tough!) are taking the lead in Polls. There was no Collusion, except by the Democrats!”

Mueller is leading the probe into potential collusion between the Trump campaign and Russia.

Trump repeatedly refers to Mueller’s team as “13 angry Democrats."

Federal Elections Commission (FEC) records show that some on Mueller's team have donated money to Democratic causes. Justice Department guidelines do not allow consideration of party affiliation to affect personnel decisions.

Special counsel Mueller himself has been a registered Republican in the past and was first appointed FBI director by President George W. Bush.

Trump tweeted that Mueller’s team should instead investigate his former rival Hillary Clinton.

Trump has repeatedly attacked the “13 Angry Democrats” in recent weeks, and he’s also accused the Department of Justice of placing a spy inside his campaign.

A top Democrat on the House Intelligence Committee said the president’s repeated claims that the FBI spied on his presidential campaign are “a piece of propaganda the president wants to put out and repeat.”

California Rep. Adam Schiff told ABC News’ chief global affairs correspondent and “This Week” Co-Anchor Martha Raddatz on Sunday that the president's assertions that the FBI infiltrated his campaign are an attempt to undermine the Mueller investigation of Russia's interference in the 2016 election and possible ties to Trump associates.

"There's no evidence to support that spy theory," Schiff said.

"You have a president peddling these falsehoods and you have essentially people putting out propaganda" to promote that "fiction," the California Democrat said. "This is part of the propaganda machine. 'Let’s spread a completely fallacious story and then let’s say that it needs to be investigated and give it a life of its own.'"

Republican Sen. Marco Rubio said he sees "no evidence" to support President Trump's claims that the FBI used an informant to gather information on his campaign, but that instead the federal probe was focused on "individuals with a history of links to Russia that were concerning."

"What I have seen is evidence that they were investigating individuals with a history of links to Russia that were concerning," Rubio, a Florida senator who sits on the Senate Intelligence Committee told Raddatz on Sunday.

ABC News' Cheyenne Haslett contributed to this report.