Axne, a first term congresswoman, was one of two Iowa Democrats to flip a Republican held district in the state in 2018, and districts like hers could be critical in maintaining the Democratic majority in the House in November.

"I believe we need a Democratic nominee who not only has the vision to rebuild our alliances and strengthen our middle class, but who can win in November - which is why I'm proud to endorse Joe Biden for President," Axne said in a statement. Axne will appear with Biden at his event in Ankeny, Iowa, Saturday evening, according to the Biden campaign's Iowa spokeswoman, Julia Krieger.

Biden now has the support of two of Iowa's three Democratic congressmembers. Rep. Abby Finkenauer of Iowa, who also turned a red district blue in the 2018 midterm elections, announced her endorsement of the former vice president earlier this month. Rep. Dave Loebsack, the third Democratic member of Iowa's congressional delegation, is backing former South Bend, Indiana, Mayor Pete Buttigieg

Biden also has the support of former Iowa Governors Chet Culver and Tom Vilsack.

Read More