Updated 4:20 p.m. |  Former state Rep. Pat Murphy, D-Iowa, will announce a bid for the Iowa House seat he lost in 2014, according to a source with knowledge of Murphy’s plans.  

Murphy will face a crowded Democratic primary field looking to take on freshman Republican Rep. Rod Blum, one of the most vulnerable House GOP incumbents in the country.  

Murphy will face a stiff primary challenge from Monica Vernon , the failed 2014 lieutenant governor nominee who has the backing of EMILY’s List — a group that backs Democratic women who support abortion rights. Vernon also has the support of a handful of local members of Congress, including Iowa Democratic Rep. Dave Loebsack and Rep. Cheri Bustos, whose Illinois district shares a border with Blum’s.  

On the same day as those close to Murphy began to reveal more information about his pending announcement, Vernon announced another high-profile endorsement. In a statement, House Minority Whip Steny Hoyer said he was “all in” for Vernon.  

“Monica Vernon is among the top Democratic candidates in the country. Her deep ties to northeastern Iowa, her hard work helping rebuild Cedar Rapids after the flood and her experience building a small business from scratch is exactly the type of problem solving that is needed in Congress today,” he said in a news release.  

Also in the field is former “Saturday Night Live” cast member Gary Kroeger. A fourth Democrat, Ravi Patel, dropped his bid last week, saying a contentious primary would not benefit his party.  

Last cycle, Murphy defeated Vernon in a similarly crowded Democratic primary in Iowa’s 1st District — which was left vacant by former Rep. Bruce Braley’s Senate bid.  

Murphy won the five-way primary with 36.7 percent. That was just barely above the 35 percent threshold that would have triggered a nominating convention, where a group of committed party activists meet to select a nominee.  

Murphy went on to lose to Blum by a 2-point margin in an abysmal year for Democrats on the ballot in the Hawkeye State.  

But sources close to Murphy said he outperformed other Democrats on the ballot, including Braley. And they say with presidential turnout he would have a good shot at victory in 2016.  

Blum is one of the most vulnerable House Republicans in 2016.  

His northeast Iowa seat strongly leans Democratic in presidential years. President Barack Obama carried it by a 14-point margin in 2012, and an 18-point margin four years earlier.  

And Blum appears unlikely to receive support from his House GOP colleagues , who have punished him for his vote against John A. Boehner for speaker earlier this year.  

Iowa’s 1st District is rated a Tossup by the Rothenberg & Gonzales Political Report /Roll Call.  

Eli Yokley contributed to this report.