Michael Franken, a retired Navy admiral and Sioux Center native, announced Monday he will join the Democratic race for Senate in an effort to unseat Republican U.S. Sen. Joni Ernst next November.

Franken released a video to the Des Moines Register highlighting his nearly 40 years in the Navy and his opposition to invading Iraq in 2002.

"I was trained to not bow to political pressure and to do what's right," he says in the video, adding that he would take that mentality to Washington, D.C.

"Republicans are afraid to ever stand up to Donald Trump," he says. "And D.C. Democrats aren't bold enough to confront the climate crisis, the health care industry and Wall Street. ... Join me, because now, more than ever, Iowans need a senator who will go against the grain in Washington to do what's right for Iowa."

The video does not mention Ernst by name, but a picture of her standing to U.S. Senate Majority Leader Mitch McConnell flashes briefly across the screen.

In an interview with the Register, Franken said Ernst has made "vacuous" promises, but, "that's not my concern."

"My concern is representing Iowa and being the best senator I can be for this state and for the nation, with a focus to the next generation," he said.

"My emphasis is to convince Iowa that the Democratic Party represents Iowans," he said. "We represent national security. We represent health security, and fair play, and non-special interests, and corporate fair play and a future that’s not belaboring our children with the deficit. So I will have a lot of messages, but the first thing I’d like to do is shake a lot of hands and let people get to know me."

Franken is the youngest of nine children and grew up in rural Iowa. He has a bachelor’s degree in engineering and a master’s degree from the College of Physics at the Naval Postgraduate School.

In Washington, D.C., he worked in a variety of roles, including for think tanks, as the first military officer on Sen. Ted Kennedy’s staff, at the U.S. Department of Defense and as chief of legislative affairs for the Navy. He retired from military service in 2017 as a three-star admiral and has been consulting in Washington, D.C.

Franken moved back to Sioux City to run for the Senate. He said he bought a house and plans to run his campaign from Sioux City.

Three other Democrats — Kimberly Graham, Theresa Greenfield and Eddie Mauro — have already launched Senate campaigns of their own.

More: Who's running for Congress in Iowa in 2020?

Local and national leaders have already begun coalescing behind Greenfield of Des Moines. She's amassed support from national groups like the Democratic Senatorial Campaign Committee and Emily's List, and she's earned endorsements from numerous local leaders such as U.S. Rep. Dave Loebsack and former Iowa first lady Christie Vilsack.

According to a report in Time magazine, Senate Minority Leader Chuck Schumer directly advised Iowa Democrat J.D. Scholten against running for the Senate, saying, "we don't need a primary." Scholten instead decided to again run for Iowa's 4th Congressional District seat.

Franken acknowledged that "there are those that would like me to wait two years" before running for the U.S. Senate — a dynamic that "absolutely" could create challenges.

"But now is my time," he said. "I'm eager for this opportunity."

Ernst, who was first elected in 2014 and is running for her second term, formally launched her reelection efforts in June at her annual Roast and Ride fundraiser.

She poses a formidable challenge to whichever Democrat survives the party's primary. Ernst tallied her highest approval rating ever in a February Des Moines Register/Mediacom Iowa Poll. At that time, 57% of Iowans approved of the job she was doing.