House Majority Leader Kevin McCarthy is officially declaring his candidacy for House speaker to replace John Boehner.
Boehner announced his resignation on Friday under pressure from conservatives.
McCarthy, who is Boehner's No. 2, sent a letter to GOP lawmakers on Monday pledging to fight for conservative principles — and asking for their support as the next speaker.
The California Republican is strongly favored to get the job though he faces a challenge from Florida Republican Rep. Daniel Webster.
McCarthy is serving his fifth term in Congress and has been endorsed by Boehner.