WASHINGTON — Beginning in February, voters will finally get the chance to pare down an unwieldy field of Republican presidential candidates and a smaller group of Democratic hopefuls, led by Hillary Clinton.
But it's not just the candidates who matter in the early contests. They have aides and stand-ins, and a collection of others without bold-faced names but who are difference-makers in the 2016 contests.
A look at a few worth watching in four-week sprint to the Iowa caucuses, set for Feb. 1.
New York billionaire Donald Trump has attracted thousands of people to his rallies and drawn millions of viewers to the Republican debates, where he has stung rivals with one-liners and baffled the professional political class with his staying power.
But telling a pollster you're for Trump is one thing. Showing up to caucus for him is something else. Winning in Iowa demands an extensive organization spanning dozens of rural communities. Trump loves talking about his lead in polls, but a loss in Iowa could affect that support.
If Trump falters against Texas Sen. Ted Cruz, who has built an advantage in Iowa, will those won over in 2015 by Trump's celebrity and unvarnished approach back him in New Hampshire? Will they shift to someone else? Pass up voting all together?
CHUCK LAUDNER AND PETE D'ALLESANDRO
Getting those Trump voters to caucus night is the job of Laudner, who has been guiding Trump's Iowa organization. A former executive director of the Republican Party of Iowa and a confidante of Iowa Rep. Steve King, one of the state's leading conservatives, he steered Pennsylvania Sen. Rick Santorum to a surprise victory in the caucuses in 2012.
D'Allesandro is a veteran Democratic strategist who is directing Bernie Sanders' Iowa team, hoping to upset front-runner Clinton. D'Allesandro, a former campaign aide to ex-Iowa Gov. Chet Culver, has worked for Sanders for months, trying to harness the Vermont senator's strength in college towns and liberal enclaves into a caucus victory.
The former president plans to hold his first solo campaign events in New Hampshire on Monday, returning to the state that nurtured his first White House race in 1992. He's long been the party's go-to surrogate and will be again as he tries to help his wife become the first women elected to the White House.
Trump is trying to spark a conflict with Bill Clinton, having spent the end of 2015 rehashing Clinton's affair with a White House intern and his impeachment past. "And she wants to accuse me of things," Trump said last week of Hillary Clinton. "And the husband's one of the great abusers of the world."
The Republicans' biggest donor of the 2012 cycle has yet to make up his mind about 2016, his political adviser said in December. Adelson appears in no hurry to put his money behind a candidate.
But the casino magnate, along with other uncommitted donors, could play a major factor in the race by delivering millions of dollars to a super political action committee in support of a candidate; most of that money would end up paying for television spots.
One thing that might be giving Adelson pause? The candidate who has spent the least on TV is Trump, while the candidate with the best-funded super PAC is Jeb Bush. The former Florida governor is mired in single digits in preference polls, despite his Right to Rise group having spent tens of millions on ads to back his campaign.
The South Carolina congressman is supporting Florida Sen. Marco Rubio. But Gowdy also has a role in the Democratic race.
Gowdy is a tea party validator for Rubio in South Carolina, which follows Iowa and New Hampshire on the Republican calendar and could be a place of reckoning for Rubio if he doesn't win in Iowa or New Hampshire. Rubio's campaign manager, Terry Sullivan, is a South Carolina native and Gowdy expects to be at the top of the senator's organization in the state.
Gowdy also is chairman of the House committee investigating the deadly 2012 attacks on a U.S. diplomatic outpost in Benghazi, Libya, while Hillary Clinton was secretary of state. Clinton testified before the panel in October, and while she appears to have moved past the issue, it's one the GOP has no plans to drop in 2016.
MATT PAUL AND MICHAEL HALLE
Hillary Clinton has made Iowa a focal point as she tries to avoid a repeat of her surprising 2008 loss in the state. Paul and Halle are at the forefront of that effort.
Paul, Clinton's Iowa director, is a longtime aide to former Iowa Gov. Tom Vilsack, now President Barack Obama's agriculture secretary, and has maintained ties throughout the state Democratic party. Those connections helped Clinton land early endorsements of several prominent Iowa Democrats, including retired Sen. Tom Harkin and two statewide officeholders who backed Obama in 2008: Attorney General Tom Miller and state Treasurer Michael Fitzgerald.
Halle is Clinton's caucus director and a veteran of Obama's first Iowa caucus campaign and campaigns in Missouri, North Carolina and Virginia. He has worked closely with Robby Mook, Clinton's campaign manager, and both helped elect Virginia Gov. Terry McAuliffe in 2013.
The populist senator from Massachusetts told The Boston Globe in September that she would likely endorse a candidate during the primaries, but has since remained coy.
Some of Warren's liberal followers migrated to Sanders, but many Democrats noticed when she praised Clinton in December, writing on Facebook that Clinton's proposals would "fight back against Republicans trying to sneak Wall Street giveaways" into a spending bill.
A Warren endorsement would be a coup for Clinton if it came before contests in Iowa or New Hampshire, across the border from Massachusetts. But if Warren backed Sanders before Iowa's caucuses, it might give him the boost needed to pull off the upset.
Colvin reported from Newark, New Jersey.