Ameritrade executive Pete Ricketts (search), describing himself as anti-abortion conservative, launched an election campaign Saturday to unseat U.S. Sen. Ben Nelson (search), the only Democrat in Nebraska's congressional delegation.

"I grew up with great values and tremendous opportunities," said Ricketts, Ameritrade's chief operating officer and son of its founder. "I want my three kids and other's people's children to have the same opportunities that I had."

Ricketts, 40, faces two other candidates in the Republican primary: former Nebraska Attorney General Don Stenberg (search) and former state GOP chairman David Kramer (search).

Nelson is up for re-election to a second term next year.

"I'm a conservative Republican," Ricketts said Saturday. "We need to support President Bush's agenda. ... We have to have a culture that respects life, that respects the unborn."

He also said that Social Security (search) should be modernized, and that private investment accounts proposed by the Bush administration "can be part of the solution."

However, he said, "I don't think they are the only solution."

Ricketts will leave his post at the Omaha-based online brokerage firm effective Aug. 26, but he will continue to serve as vice chairman and a member of Ameritrade's board of directors. His father, Joe Ricketts, is the company's founder and chairman, and the family is a big contributor to the GOP.