Republican Rep. Steve King announced on Twitter late Friday night that he would not run for Senate:

[field name = iframe]King marks the third — and highest-profile — contender to pull themselves from consideration in the last couple weeks.

Republicans considered King to be a shoo-in for the primary, and his decision leaves the GOP field wide open in the race for retiring Democratic Sen. Tom Harkin’s seat.

The Democratic field has essentially cleared for Rep. Bruce Braley.