Rep. Ron Paul (R-Texas) officially announced his candidacy for president on Friday, saying "the time is right."

"I am, today and at this moment, I'm officially announcing that I am a candidate for president in the Republican primary," Paul said on "Good Morning America." 

"Because time has come around to the point where people are agreeing with much of what I've been saying for 30 years, so I think the time is right," Paul continued. 

Paul announced last month in Iowa the formation of an exploratory committee, and his formal campaign announcement was expected. 

Paul had been planning to make what his spokesman this week called a "major announcement" on the show. This will be his third run for the White House — he was a prolific fundraiser in 2008, when he sought the GOP nomination. He also ran in 1988 as a Libertarian candidate. 

He joins a field that is finally beginning to solidify. Earlier this week former House Speaker Newt Gingrich (R-Ga.) announced his candidacy. Aside from Gingrich and Paul, highly likely candidates who have formed exploratory committees include former Massachusetts Gov. Mitt Romney and former Minnesota Gov. Tim Pawlenty. 

In total, seven candidates have jumped into the race so far. Other likely candidates could join the field in the next two weeks.

During a campaign rally in Exeter, N.H., Paul made the case that his 2012 presidential bid will be stronger than his past runs, because politics have changed to be more accomodating of his message of limited government and fiscal conservatism.

"There are many who would like to belittle this effort, but let me tell you: three's a charm," he said.

"The atmosphere was a lot different [in 2008]… It did not make all of us who believed in liberty happy," Paul added. "But boy I'll tell you what. There has been a significant change, people have awoken."

-- Jordan Fabian contributed

This post was updated at 10:27 a.m.