He announced at a press conference at the Capitol that he personally delivered his letter of immediate resignation.
"After thoughtful and prayerful consideration, I have concluded that I could be an effective state senator or an effective candidate for governor, but not both," Johnson said.
He met with Gov. Sonny Perdue shortly before the press conference. Johnson said by resigning today he would give Perdue time to call a special election in conjunction with Novembers municipal elections to fill the Senate seat for District 1 that Johnson has held since 1994.
He is the only current officeholder running to make that decision. Of the other six GOP candidates, five are in elective office, Insurance Commissioner John Oxendine, Secretary of State Karen Handel, Sen. Jeff Chapman, state Rep. Austin Scott and U.S. Rep. Nathan Deal. Only businessman Ray McBerry is not in office.
Johnson may not be able to make speeches on the Senate floor any more, but he will be able to do fund raising while most of his opponents wont. State law prohibits state officials from raising campaign contributions while the General Assembly is in session, a law that doesnt apply to Deal as a federal official.
Congressman Deal can raise money, but he is also trapped in Washington, Johnson said.
Deal is the senior Republican on the House Healthcare Subcommittee and has been in the middle of opposition to Democrats health-reform efforts. His campaign spokesman, Harris Blackwood, said Deal is staying put.
He remains fully engaged as a member of Congress and a candidate for governor, Blackwood said. He plans to actively continue both.
But Johnson said fund raising wasnt the major consideration in his decision because he feels certain hes on his way to being the top money race.
Johnson has already seen his legislative status decline since beginning his quest. As the Republican leader of the Senate when the GOP took control in 2002, Johnson became the president pro tem, the highest-ranking member of the Senate.
When his plans for higher office became known, his colleagues reminded him of a GOP Caucus rule that prohibited candidates for higher office from holding a senior leadership post.
Last session, he chaired the Senate Ethics committee rather than managing much of the Senate's operations and helped determine the course of legislation. He did push through a law that empowered his committee to recommend sanctions against senators who refused to pay their taxes.
Lt. Gov. Casey Cagle offered Johnson praise for his legislative record.
He will be greatly missed by his friends in the Senate, and we wish Eric all the best as he seeks to continue serving Georgia in a new capacity, said Cagle.