The White House has officially refused to co-operate with the impeachment inquiry against President Donald Trump.
A letter sent to Democratic leaders rejected it as “baseless” and “constitutionally invalid”.
Three Democratic-led House committees are investigating Trump.
The inquiry is trying to find out if the president held back aid to Ukraine to push it to investigate Joe Biden, who is running for the Democratic presidential nomination.
The letter came shortly after the Trump administration on Tuesday abruptly blocked a key witness in the Ukraine scandal from appearing before a congressional impeachment inquiry.