President Donald Trump lashed back at Sen. Chuck Schumer on Friday for warning him against “seat of the pants negotiating” — after the president said “attitude” was more important than preparation for his upcoming summit with Kim Jong Un.

“Obama, Schumer and Pelosi did NOTHING about North Korea, and now weak on Crime, High Tax Schumer is telling me what to do at the Summit the Dems could never set up. Schumer failed with North Korea and Iran, we don’t need his advice!” Trump said in an early morning tweet.

On Thursday, Schumer (D-NY) tweeted that “with ICBMs and nuclear warheads in the hands of North Korea, the situation is far too dangerous for seats of the pants negotiating.”

Earlier in the day, Trump responded to a question about his preparation for the historic sitdown on June 12 with North Korea’s dictator in Singapore.

“I think I’m very well prepared,” the president told reporters of the meeting to discuss denuclearization.

“I don’t think I have to prepare very much. It’s about attitude. It’s about willingness to get things done,” he said at the White House during an appearance with Japanese Prime Minister Shinzo Abe. “But I think I’ve been preparing for this summit for a long time.”