Former Florida Gov. Jeb Bush said Tuesday he will "actively explore" a run for the White House in 2016.

The son of George H.W. Bush and brother of George W. Bush - the 41st and 43rd presidents of the United States, respectively - took to Facebook and Twitter to make the announcement.

"I have decided to actively explore the possibility of running for president of the United States," Bush posted. He said he would establish a leadership political action committee to raise funds "that will help me facilitate conversations with citizens across America to discuss the most critical challenges facing our exceptional nation."

The 61-year-old ex-Florida governor, who is married to Guanajuato, Mexico-born philanthropist Columba Bush, is the "first major Republican candidate to take these kinds of steps toward a White House bid," USA Today reported. The newspaper speculated that his decision would "shake up" a GOP candidates field that might eventually include New Jersey Gov. Chris Christie, Florida U.S. Senator Marco Rubio and Kentucky Sen. Rand Paul.

Bush's announcement comes almost 23 months before the Nov. 8, 2016, presidential election. His timing should be seen as a message to Republican donors and activists that he is "dead-serious about running," an unnamed source close to Bush told ABC News.

In a mid-October ABC News-Washington Post poll on potential Republican candidates, Bush garnered the strongest support: 13 percent of GOP primary voters backed the University of Texas graduate. Among the other hopefuls, former Arkansas Gov. Mike Huckabee came in at 12 percent; Paul at 12 percent; Wisconsin Rep. and 2012 vice presidential candidate Paul Ryan at 9 percent; Florida Sen. Marco Rubio at 9 percent; and Christie at 8 percent.

Earlier this month, Bush told a Washington panel that the GOP's 2016 nominee must "lose the primary to win the general without violating your principles," which TIME magazine viewed as "an indication that he would not change his positions in order to win the nomination."

Bush, who from 1999 to 2007 led Florida for two full terms as governor, has pleaded for a more "welcoming immigration policy," which has put him at odds with some of the more conservative wings of the Republican Party. Earlier this year, Bush said even illegal immigration was an "an act of love" and "not a felony."