Michael Cohen, former personal lawyer to President Trump, urged voters Sunday to cast a ballot in the 2018 midterm elections, days after he re-registered as a member of the Democratic Party.

"The #MidtermElections2018 might be the most important vote in our lifetime," Cohen posted on Twitter.

Cohen, who served as one of the Republican National Committee's deputy finance chairmen until June, changed his party affiliation last week with the New York state board of elections in Albany. He was a Democrat until 2017, when he was asked to join the RNC in an official capacity.

Cohen started distancing from Trump as he faced growing legal pressure from federal prosecutors interested in his work for his longtime client. Cohen pleaded guilty in August before a New York federal court to a range of charges, including two related to efforts ahead of the 2016 election to silence women claiming to have had extramarital affairs with Trump.

Cohen is expected to be sentenced in December.

[Related: Stormy Daniels forgives Michael Cohen, says he 'looked like he had a weight off his shoulders' in chance encounter]