Donald Trump on Monday defended hush money payments reported by his former lawyer a day after Democrats said the U.S. president could face impeachment and jail time if the transactions are proven to be campaign finance violations.

Trump, in early morning tweets, said Democrats were wrongly targeting "a simple private transaction" after court filings last week drew renewed attention to six-figure payments by his personal lawyer to two women during the 2016 campaign so they would not discuss affairs with Trump.

On Sunday, U.S. Rep. Jerrold Nadler, who will lead the Judiciary Committee when Democrats take control of the House of Representatives next month, said if the payments were found to violate campaign finance laws it would be an impeachable offense.