Sen. Bernie Sanders vowed to “intensify” the fight against President Trump in the new year.

“Here is a New Year's Resolution I hope you will share with me. In 2018, we will not only intensify the struggle against Trumpism, we will increase our efforts to spread the progressive vision in every corner of the land,” the former Democratic presidential candidate tweeted late Sunday.

Sanders has recently called on Trump to step down over allegations of sexual misconduct leveled against him during the presidential campaign.

The Vermont senator hasn’t announced whether he will run for president again in 2020, but is seen by some as a leading contender for the Democratic nomination.