First take: Jeb Bush's 2016 plans pose many questions

Jeb Bush has weighed in, and the Republican establishment likely has its first candidate for 2016.

Bush's surprise announcement Tuesday that he will "actively explore" a 2016 bid forces potential rivals to reassess their own decisions about timing, strategy and tactics moving forward.

That's especially true of other candidates considered part of the more moderate GOP establishment, including 2012 GOP nominee Mitt Romney and New Jersey Gov. Chris Christie.

Both will have to announce soon whether they are in or out, lest Bush suck up contributions and endorsements from older-line Republicans who want one of their own to seek the White House. They'll also have to figure out how run against another Bush should they decide to get in.

Sen. Marco Rubio, a Florida Republican who shares many supporters in the state, said in October that a potential Bush candidacy would not influence his decision to run or not. "I don't think Jeb Bush, or anyone else for that matter, would make up their minds based on who else is running, and I wouldn't either," Rubio said on Fox & Friends.

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Alex Conant, a Rubio spokesman, reiterated that Tuesday. ""Marco has a lot of respect for Governor Bush, and believes he would be a formidable candidate," he said.

More maverick Republicans, particularly Sens. Rand Paul of Kentucky and Ted Cruz of Texas, may also have to move up their announcements in light of Bush's entry.

Their tactics are a little more clear. Both Paul and Cruz, Tea Party-affiliated Republicans, have criticized the party for nominating moderates like Romney, John McCain and Bob Dole, relative moderates who they say failed to excite the party's conservative base.

Expect Bush to be the new target of Tea Party backers who want one of their own as the GOP nominee.

Bush's apparent entry will force prospective candidates to assess whether they might fit into the 2016 field. This is particularly true for governors or ex-governors who are considering the race, including Rick Perry of Texas — a major source of funding for the Bush family — Mike Pence of Indiana, Bobby Jindal of Louisiana and John Kasich of Ohio.

Some Democrats may also recalibrate their candidacies in light of Bush's announcement.

Hillary Rodham Clinton, for example, has been criticized as a retread who may be a tad old for the presidency — issues that would likely go away if Bush becomes the third member of his family to seek the Oval Office.

Another candidate must also reassess after Tuesday's announcement: Jeb Bush himself. The son of one president and brother of another brings a proven ability to raise money but other baggage. Conservative skeptics of the latest family candidacy developed a new hashtag for critical tweets: "StopJebBush."

Opponents are already raising questions about Bush's business dealings and his two terms as governor of Florida — an administration that ended in 2006.

The latest Bush presidential hopeful will also have to answer a fundamental question: Why should Americans extend his family's presidential dynasty?