Democratic Rep. Bruce Braley opened the floodgates of ambitious pols eyeing his Iowa district when he announced his Senate bid Thursday.

Hawkeye State operatives expect a deep and competitive field for the Democratic-leaning 1st District, which is anchored by Cedar Rapids, Dubuque and Waterloo in eastern Iowa.

The dominoes tipped last month when Democratic Sen. Tom Harkin announced he would not seek a sixth term, creating the first open-seat Senate race in Iowa in four decades. Braley is the only announced candidate, but GOP Reps. Steve King and Tom Latham are considering bids.

Here’s a look at the early names Democrats floated for Braley’s House seat:

• State Rep. Tyler Olson, who was just elected state party chairman a few weeks ago, confirmed his interest in the race Thursday with CQ Roll Call. He said: “Sen. Harkin came and announced that he was not going to run again because he thought it was time for some new ideas and fresh faces. I think that’s why he asked me to lead the Democratic Party, and the best way to do that may be a run for Congress.”
• State Sen. Liz Mathis enjoys a high profile from her time as an evening news anchor in Waterloo.
• State Rep. Pat Murphy, a former state House speaker, said he would begin a bid for the House as soon as Braley announced his Senate candidacy.
• State Senate President Pam Jochum told the Des Moines Register recently that she would take a look at the seat.

• 2010 and 2012 GOP nominee Ben Lange
• Former Cedar Rapids Mayor Paul Pate
• Businessman Rod Blum, who lost a close primary race with Lange last year