WASHINGTON -- A top aide to President Barack Obama says the White House takes seriously the possibility that Republicans in the House of Representatives could pursue impeachment of the president.

Impeachment is seen as an extremely unlikely, but has been discussed by some conservative figures.

Senior White House adviser Dan Pfeiffer told reporters Friday that Republicans have already "opened the door for impeachment" by contemplating suing Obama over his use of executive authority. He says that any further executive action Obama may sign this year on immigration will "up the likelihood" of Republicans pursuing that path.

Pfeiffer was dismissive about how good a case Republicans could make to come up with impeachable offences. But he says it would be foolish to discount the possibility that Republicans would at least consider pursuing impeachment.