Newt Gingrich, the architect behind the 1994 Republican revolution, officially announced he's running for president via Twitter.
Gingrich, a former House speaker, is the first major candidate to declare a run for president with a tweet.
"Today I am announcing my candidacy for President of the United States. You can watch my announcement here. http://bit.ly/kEbh7d," he wrote to his 1.3 million followers on Twitter.
Since leaving Congress more than a decade ago, Gingrich, 67, has built something of an empire, a network of conservative advocacy groups that includes American Solutions, Center for Health Transformation, Gingrich Productions and Americano. Together, the groups have raised more than $32 million in the past two years.
In addition to his fundraising and coalition building, Gingrich has also taken a hard line against President Obama. While Obama's approval rating has jumped to 60 percent since Osama bin Laden's killing May 1 -- and more than half of Americans said he "deserved" be re-elected -- the president's numbers could settle back down. An ABC News/Washington Post poll taken before bin Laden's death found 45 percent of Americans surveyed said they would "definitely" not support Obama's re-election, with 57 percent saying they disapproved of his handling of the economy.
Gingrich is working to capitalize on that discontent, ripping the president in recent months for his handling of the BP oil spill, the repeal of "don't ask, don't tell" and his recent military actions in Libya, although a May 4 Quinnipiac poll suggests Gingrich might have a steep climb too: Forty-two percent of poll participants said they would "never" vote for him. Only Donald Trump and Sarah Palin scored higher -- both at 58 percent -- in the "never" vote for category among potential Republican presidential candidates.
"We need a commander in chief with the courage to tell the truth -- not a commander in chief who is confused about whether his job is kicking a soccer ball or leading the United States," Gingrich said in March, referring to pictures of the president playing soccer with local kids on his foreign trips.
Gingrich will likely position himself as "the conservative with experience," harkening back to his crafting of the Republican revolution 17 years ago. When, as House speaker, Gingrich unveiled the "Contract With America" on the Capitol steps, he called it "the boldest, most decisive, clearest contract in the history of the United States."
It helped the Republicans win control of the House for the first time in 40 years. Gingrich's battles with President Clinton led to two government shutdowns but also helped produce budget surpluses and sweeping welfare reform.
Gingrich's biggest problem may be baggage, both political and personal. He resigned from Congress in 1998 after his party suffered massive midterm losses, and amid a barrage of ethics complaints.
It later came out that he'd been having an affair with a staff member, Callista Bisek, while leading the impeachment proceedings against Clinton for allegations of perjury in the Paula Jones sexual harassment civil case and in Clinton's affair with Monica Lewinsky. Gingrich married Bisek in 2000, making her his third wife.
Gingrich has been divorced twice, explaining his infidelities to the Christian Broadcasting Network as triggered by passion for his country:
"There's no question that at times in my life, partially driven by how passionately I felt about this country, that I worked far too hard and that things happened in my life that were not appropriate," Gingrich said.
Gingrich's campaign will launch with a sprint: He's already set up a campaign headquarters in Atlanta, hired a campaign manager and in the next week plans to deliver speeches in Washington and Atlanta, followed by a commencement address at Eureka College, Ronald Reagan's alma mater. Then he's off to Iowa, where he'll hold a dozen campaign events over four days.
ABC News' Karin Halperin contributed additional reporting to this story.