US President Donald Trump faced two deadlines in Congress on Sunday as Democrats prepared to shift the focus of their impeachment inquiry from fact-finding to the consideration of possible charges of misconduct over his dealings with Ukraine.

The Democratic-led House of Representatives Judiciary Committee, tasked with considering charges known as articles of impeachment, has given the president until 6 p.m. EST (2300 GMT) on Sunday to say whether he or his legal counsel will participate in an impeachment hearing on Wednesday.

The hearing, the first in a series of proceedings expected before the committee, will hear testimony on the impeachment process established under the US Constitution from a panel of legal experts that has yet to be named.

Hearings before the committee, which has responsibility for crafting any formal charges against Trump, are a major step toward possible charges. Democratic House Speaker Nancy Pelosi, who will make the final decision, has not said yet whether the Republican president should be formally impeached. But in a letter to supporters last week, she called for him to be held accountable for his actions.

Trump has denied any wrongdoing and called the impeachment inquiry a witch hunt aimed at unseating a democratically elected president.