MANCHESTER, N.H. -- Democrats are preparing for a long and expensive head-to-head battle between Hillary Clinton and Bernie Sanders.

Clinton and Sanders are both flush with campaign cash. Clinton has overwhelming support among Democratic Party leaders, but Sanders foresees staying competitive by drawing new and younger voters into the primary process.

"I believe [Sanders] will have the resources to push this campaign well into the spring, and we recognize this," Clinton campaign manager Robby Mook told reporters this week.

On the heels of Clinton's narrow victory in Iowa, both she and Sanders are competing aggressively in New Hampshire, which holds its primary on Tuesday. Sanders has held a solid lead there for weeks, leaving Clinton's goal to pull off a stronger-than-expected finish.

But as they vie for victory in New Hampshire, their campaigns are zeroing in on contests that fall later in the primary calendar. More than half of the delegates up for grabs in the Democratic race are on the table in March, with an 11-state voting bonanza known as Super Tuesday on March 1.

Even Sanders' recent back-and-forth with Clinton over adding more debates was steeped in delegate strategy.

When Clinton requested that a debate be held in Flint, Mich., which is dealing with a crisis over lead contamination in the city's water, Sanders made sure the contest was scheduled before the state's March 8 primary. He also successfully negotiated to hold another debate in California, which awards a large cache of delegates in its June primary.

Sanders wanted a debate in New York City, another delegate-rich target, but he was rebuffed. So now he's turned his sights toward Pennsylvania, which offers its own delegate haul.

Clinton already has an edge in the primaries after gaining public but nonbinding support from superdelegates, the party leaders who can support the candidate of their choice at the Democratic National Convention. According to an informal survey of those superdelegates by The Associated Press, Clinton has 385 delegates and Sanders has 29.

It takes 2,382 delegates to win the Democratic nomination for president.

But Sanders' small-donor network and his fundraising strategy have proved capable of competing with Clinton's establishment backing.

Clinton began 2016 with about $38 million in campaign cash, $10 million more than Sanders had. Both saw their war chests grow bigger in January, with Sanders saying he'd raised $20 million last month and Clinton netting another $15 million.

Their fundraising reports for the last three months of 2015 showed Clinton has made a bigger investment in staffing. Sanders spent about $4 million on payroll and payroll taxes in that time; Clinton, almost $11 million.

Clinton has slightly outspent Sanders on radio and television spots aired so far, according to political advertising tracker Kantar Media's CMAG data. Through Friday, Clinton has spent $23.4 million. Sanders has spent $22.1 million. But Sanders has put substantial resources into the long game. He's aired about $1.6 million in ads in Nevada, where Clinton has spent about $1 million so far.

Sanders also has about double the amount of TV and radio spending planned over the next few weeks. He's lined up about $1.5 million in future ads, compared with about $730,000 for Clinton, the data show.

Meanwhile, Republicans are preparing for their own lengthy campaign with a slowly shrinking field of candidates.

Marco Rubio shouldered intensifying attacks Friday from moderate-leaning Republicans who fear that a strong showing by Rubio in Tuesday's New Hampshire primary could spell the end for their presidential campaigns.

Jeb Bush and Chris Christie both accused Rubio of a lackluster set of accomplishments. Bush summed up the senator's achievements in one word: "nothing."

"Marco is a talented politician," Bush said on MSNBC. "He's a great guy, but he's not a leader."

Rubio did pick up another endorsement from a one-time rival -- former Louisiana Gov. Bobby Jindal, who dropped out of the race in November.

Ted Cruz, the victor in Monday's Iowa GOP caucuses, faced new accusations about his campaign's practices from Ben Carson, who called Cruz out for "dirty tricks." Cruz's campaign had distributed ads ahead of the Iowa caucuses that Carson had dropped out of the race.

"I'm not saying that it rises to the level of Benghazi, I'm saying it's the same kind of attitude," Carson said. "The attitude being: It's water under the bridge."

In another development this week, ABC News dropped Carly Fiorina from tonight's debate in New Hampshire, where the former technology executive has campaigned vigorously.

A top New Hampshire member of the Republican National Committee criticized that decision.

"The stage has plenty of room," Steve Duprey, chairman of the party's debate committee, wrote on his Facebook page Thursday night. "Whatever chance she might have had is negated by not allowing her on stage."

Fiorina herself took to the blogging site Medium to argue "the game is rigged" by the media and political parties.

ABC chose the debate lineup on the basis of criteria previously agreed upon, including performances in the Iowa caucuses and averages of recent New Hampshire polling. ABC declined to comment on New Hampshire Republicans' calls for Fiorina to be on stage.

Information for this article was contributed by Lisa Lerer, Julie Bykowicz, Chad Day, Stephen Ohlemacher, Kathleen Ronayne and Dave Bauder of The Associated Press.

A Section on 02/06/2016