Decrying what he called “a partisan impeachment crusade,” President Donald Trump wrote a letter Tuesday to House Speaker Nancy Pelosi, accusing the California Democrat of “violating your oaths of office, breaking your allegiance to the Constitution, and ... declaring open war on American democracy.”

Read the president’s letter here.

> If letter does not appear above, you can see it here

Trump faces two articles of impeachment by House Democrats: abuse of power and obstruction of Congress.

»RELATED: Georgia's Collins delivers scathing dissent of Judiciary Committee impeachment report

A Senate impeachment trial could begin as soon as Jan. 9.

»IMPEACHMENT TRACKER: How Congress is trending

Trump would become only the third U.S. president to be impeached, following Andrew Johnson and Bill Clinton.