By Marie Horrigan, CQ Staff

South Dakota Democratic Sen. Tim Johnson , who suffered a near-fatal brain hemorrhage, has publicly declared for the first time that he will run next year for a third Senate term — a statement that coincided with his first return to his home state since his sudden health crisis in December.

Johnson’s decision to run, which came after months of recovery and rehabilitative therapy, ended speculation about whether he was healthy enough to undergo the rigors of a re-election campaign. It also shelved Democrats’ concerns that they would have to defend an open seat in South Dakota — a state that generally leans Republican — as they seek to protect or extend the razor-thin Senate majority they won in the 2006 elections.

Among his other activities, Johnson discussed his decision to seek re-election in an interview with Bob Woodruff of ABC News, which will air late Tuesday night on the network’s “Nightline” program. Johnson’s decision to provide the exclusive interview to Woodruff was not a coincidence: The former anchorman of ABC’s “World News Tonight” sustained traumatic brain injuries himself while reporting on the war in Iraq.

A welcome-back event Tuesday in Sioux Falls marked Johnson’s homecoming and first public event since Dec. 13, when he suffered bleeding on the brain caused by a congenital condition known as arteriovenous malformation. Johnson has undertaken months of intensive daily physical therapy to recover full mobility and clearer speech. Johnson said in his remarks that his speech was not “100 percent,” but was expected to continue improving.

“I am back,” he declared to a friendly audience in South Dakota’s most populous city.

“I promise you all that I will work harder than ever for you and for our state,” said Johnson in prepared remarks provided by his Washington Senate office. “Not everyone gets a second chance at life. My commitment to you for my second chance at life is to make you and all South Dakotans the beneficiary of that gift.”

The stakes were high for Johnson’s first appearance, the first chance voters had to evaluate his health and abilities to execute the duties of his office. The event, at the Sioux Falls Convention Center, was funded by Johnson’s re-election campaign.

Johnson’s re-election campaign also launched a Web site to commemorate the senator’s return. The Web site included an online card that supporters could sign, which said in part: “Welcome back, Senator Johnson. You have been missed. We could not be happier that you are back home once again.” Data culled from those signing the online card — name, e-mail address and physical address A-— would be used for “campaign-related purposes,” according to the Web site’s privacy note.

Though Johnson has been sidelined from campaign activities since taking ill, Democratic Party surrogates made sure the senator had enough money to launch a campaign should he decide to run for re-election. They helped his campaign committee raise $1.3 million in the first six months of 2007, a bundle that left him with a hefty $1.8 million cash on hand as of July 1.

Two Republicans have signed up to challenge Johnson: state Rep. Joel Dykstra and businessman Sam Kephart. Both filed as candidates with the Federal Election Commission (FEC) after the end of the second-quarter fundraising period and will file their first campaign finance reports by Oct. 15 for the year’s third quarter, which runs through the end of September.

Republicans insist they can take the South Dakota seat, pointing to Johnson’s cliffhanger win by a 524-vote margin in 2002 over Republican John Thune , then the state’s at-large House member, and Thune’s subsequent narrow upset win over Democratic Sen. Tom Daschle in 2004 — a year in which President Bush carried South Dakota at the top of the Republican ticket by a margin of 22 percentage points.

But two-term Gov. Michael Rounds , the GOP’s potentially toughest 2008 opponent to Johnson, appears increasingly unlikely to run. Rounds has never publicly expressed interest in the race, and even spoke at Johnson’s welcome-home rally Tuesday. Rival-turned-colleague Thune provided a taped greeting for the event.

Also on the speakers’ list was Democrat Stephanie Herseth-Sandlin , who has been the state’s sole House member since winning a special election in 2004. Herseth-Sandlin was subject to speculation that she would run for the Senate if Johnson could not, so she now is in a position to focus her political attentions on a 2008 House re-election campaign in which she is strongly favored to win.