Sen. Rand Paul (R-Ky.) is organizing his political team for his expected presidential run, ion Tuesday tapping consultant Chip Englander as his campaign manager. (Lauren Victoria Burke/AP)

A broad field of GOP candidates are ramping up preparations for presidential runs in the wake of early maneuvering by establishment favorites Jeb Bush and Mitt Romney, kicking off the race for the 2016 Republican nomination at a breakneck speed.

Sen. Rand Paul of Kentucky, who is making a swing through New Hampshire on Wednesday, has tapped a campaign manager for his expected bid, while New Jersey Gov. Chris Christie is quietly mobilizing the group of wealthy donors who would finance his effort.

Other possible contenders — such as former senator Rick Santorum of Pennsylvania, Sen. Marco Rubio of Florida, former Arkansas governor Mike Huckabee and former New York governor George Pataki — are holding meetings with party activists and donors, emphasizing their interest in running.

“Jeb Bush and Mitt Romney both threw a very interesting wrench in the mix,” said GOP strategist Saul Anuzis, former chairman of the Michigan Republican Party. “I don’t think anybody expected them to come out so early or to come out so forcefully. If everybody stays in, it’s truly a wide-open ballgame.”

Christie and Wisconsin Gov. Scott Walker sought to use separate State of the State addresses Tuesday to lay out rationales for their anticipated GOP bids, underscoring how 2016 considerations are now driving state and national politics on the right.

Could the third time be a charm for Mitt Romney? The former Republican presidential candidate is making moves to explore another possible White House bid. The Post's Karen Tumulty explains what's happening behind the scenes, and what it could mean for the 2016 GOP field. (Julie Percha/The Washington Post)

While there is not a single declared candidate, the rush of behind-the-scenes activity spotlights the crowded and costly nature of the coming intraparty fight. With as many as two dozen contenders, the race is shaping up to be one of the largest and most competitive in modern presidential politics.

“I think everyone is looking at the race right now,” Sen. Ted Cruz (Tex.) said Tuesday on Fox News. He included himself in that group, and he will travel to Iowa this month to address a conservative gathering.

The rapid developments resemble the rush in early 2007, when candidates on both sides were quick to position themselves for White House runs.

This time, however, there is a marked lack of jockeying on the Democratic side, which has largely coalesced around an expected campaign by former secretary of state Hillary Rodham Clinton.

President Obama’s pollster, Joel Benenson, has signed on as Clinton’s chief strategist and pollster, while Jim Margolis, who handled the Obama campaign’s advertising, will be her media adviser, according to Democrats familiar with the moves.

The initial GOP campaign — set in motion by Bush’s declaration last month that he was actively exploring a campaign — has been roiled by Romney’s sudden, intense interest in a third White House bid.

The former Massachusetts governor has spent recent days reaching out to donors, former aides and party leaders, convincing many who have spoken with him that he has made up his mind.

“He will absolutely do it,” said a person close to Romney who requested anonymity to discuss private conversations. “It’s a matter of when.”

In calls with GOP allies Tuesday, Romney laid out his take on the upcoming contest and tested a new message that blends hawkish foreign policy views with a revised agenda on economic empowerment for poor and working Americans.

“It’s been exciting to see the outpouring of encouragement,” Spencer Zwick, Romney’s 2012 national finance chairman, said in an interview. “If he runs, he’ll have significant support.”

Romney plans to address party leaders Friday at the Republican National Committee’s winter meeting in San Diego. Meanwhile, top advisers Zwick and Beth Myers and former Utah governor Mike Leavitt are discussing what kind of political vehicles Romney would need to set up before an announcement. A pro-Romney super PAC would probably take on a bigger share of tasks than the super PAC backing him did in 2012, lessening the pressure on the campaign to raise money under strict contribution limits.

Among the other issues under consideration: where to locate a campaign headquarters and what role would be played by consultant Stuart Stevens, a polarizing figure among many Romney donors and allies.

One Romney ally, Rep. Jason Chaffetz of Utah, said in an interview Tuesday that a swell of “buyer’s remorse” would lift Romney, adding: “I don’t know how excited anybody could be with Jeb Bush’s candidacy.”

Other House Republicans are cooler to the idea. Speaking to reporters Tuesday at the Capitol, Speaker John A. Boehner (R-Ohio), who has encouraged Bush to run, declined to say much about Romney.

“Well, I’ll let him make that decision,” Boehner said. “There will be a lot of candidates making announcements in the coming months, I expect, and it’s a very open process. May the best person win.”

Romney, who lost decisively to Obama in 2012, has been making the case to former donors that he would prevail in another campaign because, as he put it, “I’ve been vindicated,” according to people familiar with the conversations.

That argument has not been persuasive to some major party financiers. “It is mystifying most of them,” said one highly placed GOP operative who is in contact with wealthy party donors, adding: “This doesn’t look like it was well thought out and organized.”

Bush and his advisers and donors have watched Romney’s moves with some incredulity, according to people familiar with their thinking. Romney’s aggressive posture has also offered them a bit of relief, taking some of the political heat and press attention away from Bush, whose team is intently focused on fundraising.

In the coming weeks, Bush plans an ambitious rollout of an expanded political and financial team, aimed at highlighting how swiftly he has amassed support within the party, especially among leading donors.

Christie, whose advisers were startled by Bush’s entry last month, is moving to assemble his own finance operation.

Dallas investor Ray Washburne, who declined to comment for this article, has signed on to serve as finance chairman for the expected campaign, according to people familiar with his plans. Christie is also preparing to set up a leadership PAC as early as this month, the New York Times reported Tuesday.

Christie is not expected to make a public announcement until after attending the inauguration of a crop of new GOP governors he helped elect as chairman of the Republican Governors Association, including Larry Hogan of Maryland, who is being sworn in next Wednesday.

But he used his State of the State address Tuesday in Trenton to lay the themes of a national run, calling the United States a “nation beset by anxiety,” a place where it seems that “leaders in Washington . . . stoke division for their own political gain.”

He called for an “American renewal” and a “New Jersey renewal” that will help expand a state and national economy that he said are not growing fast enough.

Walker, in his State of the State address Tuesday in Madison, derided “top-down regulations and mandates from the federal government” and said he is working with the state’s attorney general to prepare a lawsuit challenging proposed federal energy regulations. He also called for the consolidation of a number of state agencies, arguing that streamlining government must happen at the state and federal level.

“Some in Washington believe government should play a growing role in our lives and rarely question its expanse. Others have such disdain for government that they attempt to keep it from working at all,” Walker said. “Instead, we have a chance to lead here in Wisconsin.”

Walker even got in a dig at Christie, who was photographed hugging Dallas Cowboys owner Jerry Jones in Jones’s owners box after a Cowboys victory earlier this month. The Green Bay Packers beat the Cowboys in a playoff game Sunday.

“I had plenty of fun hugging owners in the stands at Lambeau Field,” Walker said. The Packers are publicly owned.

Paul, meanwhile, is organizing his own political team.

On Tuesday, he tapped consultant Chip Englander, 33, who recently led Republican Bruce Rauner’s successful run for Illinois governor, to serve as his campaign manager for his likely bid. Doug Stafford, Paul’s longtime confidant, will remain as his chief political adviser.

The move captures Paul’s unorthodox approach to presidential politics and his expected candidacy, with an emphasis on outreach to poor and younger voters while courting conservative activists in early-primary states.

Dan Balz, Anne Gearan, Karen Tumulty and Katie Zezima contributed to this report.