The former governor, who resigned as U.S. agriculture secretary last month, said he took Nebraska with him as he worked in the Cabinet on farm issues. He quit that post to seek the Senate seat to be vacated at the end of next year by Republican Chuck Hagel.
"Now, Steph and I start a new chapter, a chapter where we go across this state to earn the trust of Nebraskans again _ to be your United States senator," Johanns said in the video, mentioning his wife, Stephanie.
The video was embedded on Johanns' campaign site but hosted by the video-sharing site YouTube. Johanns planned a three-day, 13-city tour of the state beginning later Wednesday to discuss his campaign, starting in Omaha and ending in Scottsbluff on Friday.
Johanns said he has the leadership necessary to push a Senate agenda of less government, lower taxes and true border security.
"He is the right man at the right time who is best able to represent Nebraskans' vote in the United States Senate," Republican Gov. Dave Heineman said at Johanns' in-person announcement in Omaha.
Two other Republicansare also running for the Senate seat: Attorney General Jon Bruning and Schuyler businessman Pat Flynn.
No Democrats are in the race yet, although former U.S. Sen. Bob Kerrey has said he will decide soon whether to leave his college post in New York and return to Nebraska politics.
State Democrats renewed criticism of Johanns for leaving his Cabinet post in the middle of negotiations on the farm bill, and for authorizing the closure of 10 farm service offices in Nebraska.
"Mike Johanns has already demonstrated what kind of U.S. senator he would be," Democratic Party Chairman Steve Achelpohl said. "When he went to Washington, he left his Nebraskavalues behind."
The Democratic Senatorial Campaign Committee also lashed out at Johanns, with spokesman Matthew Miller saying Johanns "has a long history of putting his own ambition ahead of anything else."