With a seven-paragraph Facebook post on Tuesday, Jeb Bush instantly transformed the nascent campaign. His decision to "actively explore" a presidential bid accelerates the scramble for donors. It also gives the former Florida governor time to figure out how to overcome suspicion in the Republican base while positioning himself as the establishment candidate in a fragmented field.

The pre-holiday timing of the announcement was a big surprise to many beyond Bush's tight inner circle. Most of the political spotlight has been on Hillary Clinton this year, leaving GOP donors to sit back, hedge their bets and watch the field develop.

But Bush's decision to make a move now -- 13 months ahead of the Iowa caucus -- speaks to the complicated political decisions facing potential 2016 GOP candidates. They can maintain the coy stance of insisting they haven't made a decision on running, wait out the calendar and hopefully avoid a long, bruising primary like the one that left Mitt Romney damaged in 2012. Or they can start the work now to capture the staff and donors that can take on the Clinton machine.

Bush chose option B.

After all, many GOP donors and operatives, who have serious doubts about much of the field but remain uneasy about the prospect of a bruising primary, have been waiting for a clear signal from either Bush or Romney, who is being pressured by many of his longtime supporters to make a third presidential run.

Bush, until recently, seemed unsure about confronting the rigors of a race. Charlie Black, who chaired Sen. John McCain's 2008 presidential run, said that prompted his potential opponents who were jockeying for establishment-minded donors to raise doubts about his interest in the race -- doubts that seemed to motivate Bush to plant a flag.

"Some of the other candidates out there have been competing for some of those dollars and some of those donors — and some of them have been implying here and there that Jeb wasn't interested," he said.

Now Bush has signaled he's serious and can begin to lock down commitments from those donors — making it a tougher race for many of his opponents.

Bush "froze the donor sector of the hidden primary," said Florida-based Republican strategist Rick Wilson, noting that by stepping one foot into the race so early Bush has created a far steeper climb for New Jersey Gov. Chris Christie. "All those Wall Street donor types who absolutely loved Chris Christie a year and a half ago, and cooled off to him a year ago, are now not returning his phone calls. He's undisciplined. They kept seeing it over and over again."

There are grave concerns within the Republican Party about whether Christie can recover from the George Washington Bridge scandal and whether voters will appreciate his bravado. Centrist Republicans view Kentucky Sen. Rand Paul with skepticism, despite his grassroots base and determined drift toward more palatable positions on foreign policy. While Texas Gov. Rick Perry appears to be making all the right moves -- enlisting tutors and meeting with activists—he has yet to convince the party faithful that he can pick up the pieces from his disastrous 2012 run. Other potential candidates like Florida Sen. Marco Rubio have intrigued Republican voters, but still have a long way to go before demonstrating they can command the field.

Al Cardenas, a close Bush family ally and GOP lobbyist, said he doesn't believe Romney will run if Bush becomes the clear frontrunner in the race.

"I've spoken with Mitt Romney, who I consider to be a great friend and a great leader, about 2016, and I've always been under the assumption if people he trusts like Jeb Bush decide to run that he would not decide to do that," he said.

But other operatives close to Romney said Tuesday they did not think Bush's decision would foreclose a Romney run. That could create a situation where donors remain on the sidelines well into the spring to avoid choosing sides. Though the two men have expressed mutual admiration for one another, they are not close.

By announcing the formation of a leadership PAC and signaling his intentions so early, Bush at once acknowledged his considerable advantages and vulnerabilities -- including his positions on immigration and education reforms -- as he mulls a final decision. He comes to the race with a committed core of donors, who date back to his father and brother's bids for the White House, and his allies have been building the Bush 2016 finance team now for several months.

Bush's establishment of a leadership PAC — a step that falls well short of a formal exploratory committee — will also allow him to travel freely to early primary states to test the length of his brother's shadow on his potential presidential campaign. Fatigue from the Bush years, stemming from the expansion of federal spending and the U.S. military entanglements in Iraq and Afghanistan, was a huge drag on Republicans in 2006 and 2008.

But George W. Bush's favorability ratings have rebounded since they hit their low of 32% in April 2008, according to polling by Gallup. Earlier this year, a Gallup survey showed that 53% of American voters now view George W. Bush favorably. Former President George H.W. Bush's approval ratings in that survey—63%— were just a point shy of the high marks given to former President Bill Clinton.

Still some Republicans did not mince words on Tuesday about the drawbacks of the Bush name.

"I can't see the country electing another Bush," Sen Tom Coburn told reporters off the Senate floor. "I love Jeb Bush — I think he's a nice guy. I just can't see it."

"There are still hard feeling about George W.," Coburn continued. "So you start out with a negative - (because) you've got the wrong last name. If he didn't have that last name he'd be a pretty good candidate."

Still, there is a large cadre of former Bush donors who backed Romney in 2012, and the former Florida Governor now can test their willingness to come back into the fold -- even as a Romney run hangs as a possibility.

Of equal importance, Bush now has a long lead time to confront the most formidable challenge facing his bid: winning over core Republican activists in the early states of Iowa, New Hampshire and South Carolina who vehemently disagree with his moderate stance on immigration reform and his support for Common Core educational standards.

He signaled his strategy on that front -- and the fact that he will not be cowed by activists hostile to his bid -- during a Wall Street Journal CEO Council meeting earlier this month when he said the GOP presidential nominee shouldn't violate their principles to win the primary.

By giving himself a year to begin the courtship of activists in Iowa, New Hampshire and other early states, former New Hampshire GOP committeeman Tom Rath said, Bush "is taking these issues on and letting them play out -- and they typically lose a lot of their punch when they are played out and discussed over time... This gives a lot of time to let the air go out of some of those balloons."

"If you look at the race basically as geography, he defines a very important part of that geography: the center-right governing conservative spot on the map," added Rath, who supported Romney in 2008 and 2012, "and that typically is the person that we nominate."

Longtime Iowa political observer Craig Robinson, said Bush's announcement caught many Republican activists in Iowa off guard because he has spent so little time there, but it was viewed Tuesday as a wise move.

"He needs a longer period of time to communicate to people where he is on education. He's going to have to explain what he wants to happen on immigration," said Robinson, former political director of the Iowa GOP and editor of the Iowa Republican, a website. "There's really only one spot for an establishment candidate in Iowa.... And it's as wide open as it's ever been."

Kevin Madden, a Republican strategist, noted that Bush's early decision will allow him to lock down staff with expertise in those key states, who can begin the easing the concerns of activists in earnest -- highlighting his conservative record as governor of Florida and tackling questions about his current positioning on education and immigration.

"Every single candidate has an 'oppo' book with their name on the front cover," Madden said. "The difference between those candidates winning and losing is the team you put together and the strategy that you execute to overcome many of those vulnerabilities and put yourself in a position to win."

New Hampshire Senator Kelly Ayotte hinted at the difficulty of that spade work ahead for Bush and all of the 2016 candidates in an interview Tuesday.

"He hasn't really been to New Hampshire yet," she said when asked about Bush's announcement. "I don't care who you are, you have to do the hard work in New Hampshire.... Obviously, coming into it with the Bush name, he'll have name recognition. But I think everyone will get an open vetting in New Hampshire."