WASHINGTON (CNN) -- Former Iowa Gov. Tom Vilsack formally endorsed Sen. Hillary Clinton's bid for the White House Monday, a month after he ended his own candidacy for the Democratic presidential nomination.

"Senator Clinton has traveled the world, understands world leaders, knows world leaders, and has a relationship with those world leaders, and she can begin from the very first day as president to begin to repair the tarnished image the united states has had under the Bush Administration," Vilsack said in a press conference in Des Moines, Iowa with Clinton at his side.

"She is prepared to run a tough race, and win that race," he added.

Vilsack has already started raising money for the New York Democrat ahead of the March 31 Federal Elections Commission filing deadline. In an e-mail solicitation sent Monday morning, he wrote, "Of all the candidates running, she has the best ideas, the most energy, and the values and vision to lead our country in the right direction."