WASHINGTON -- Sen. Benjamin L. Cardin's telephone began ringing months ago. On the line: representatives of the Democratic presidential contenders soliciting advice on Maryland politics, asking about lessons learned from his 2006 Senate race or just checking in again to gauge his latest thoughts on the campaign.
But the callers are after more than his wisdom. As a superdelegate to the Democratic National Convention, Cardin will not be bound by the results of next month's Maryland primary election when he casts his vote in Denver this summer, but may back whichever candidate he chooses.
Having declined to declare his intentions in a tightening race, he can expect the feelers to increase.
"It's clear that part of it is they understand I have a vote at the convention, and they know that my vote is uncommitted," says Cardin. "They want to establish a political relationship."
Of the 99 delegates whom Maryland Democrats will send to the national convention in August, 70 will be required by party rules to vote according to the results of the state primary Feb. 12.
But the 27 superdelegates - Gov. Martin O'Malley, the Democratic members of the state's congressional delegation and other party officials - face no such restrictions. (Two more delegates to be selected by the state party in May will enjoy similar freedom.)
Such free agents will make up a fifth of the nominating convention, and most remain undeclared.
If none of the candidates has secured a majority of delegates by the time the race reaches Denver, the superdelegates could decide which Democrat goes up against the Republican nominee this fall.
"In the past, the presidential candidates would seek the endorsements of superdelegates simply to establish their credibility," says the Montgomery County Democrat, who also has remained neutral. "Now it's not just whether or not it's helpful politically. The superdelegates could hold the key to the outcome."
That potential is not lost on the candidates.
While they're crisscrossing the country, making speeches and wooing primary voters, their aides are conducting what amounts to a parallel campaign, reaching out to superdelegates and negotiating for support.
"It's retail politics among the elites," says Thomas Schaller, a professor of political science at the University of Maryland, Baltimore County. "If we get to the point where it's late in the cycle and Edwards is holding 10 or 15 percent of delegates so nobody's going to get to 50, then it becomes this intraparty battle. ... Then it will become, 'What can you promise me, and why should I pair up with you?'"
The attention to superdelegates is a Democratic phenomenon. The Republican nominating process doesn't include superdelegates; all of the participants in the Republican National Convention in Minneapolis in September will be required to vote according to the results of their state primaries.
Among the Democrats, Clinton leads with declarations of support from 166 superdelegates to go with the 24 delegates she won in Iowa and New Hampshire for a total of 190 overall, according to a running tally kept by CNN. Obama has 78 superdelegates and an overall total of 103; Edwards has 33, and a total of 51.
That leaves more than 500 superdelegates up for grabs. It will take 2,025 delegates to clinch the nomination.
In Maryland, O'Malley, Sen. Barbara A. Mikulski and Rep. C.A. Dutch Ruppersberger have endorsed Clinton; Reps. Elijah E. Cummings and Albert R. Wynn are backing Obama.
But two-thirds of the state's superdelegates - including Cardin, Van Hollen, House Majority Leader Steny H. Hoyer and Rep. John Sarbanes - have remained neutral.
Cardin has made endorsements in the past - he was an early backer of Bill Clinton - but says he doesn't plan to announce a choice until after the Maryland primary.
"I like all the major candidates," says Cardin, who serves on Senate committees with Clinton and Obama. "Quite frankly, I think it's a close call. At this point, I see it would not be helpful for me, from my own point of view, to tell the people who I think would be the best president, because I'm not clear yet."
Hoyer, like other members of the congressional leadership, says he is staying out of the primary campaign. The same goes for Van Hollen, who chairs the Democratic Congressional Campaign Committee.
"We need to work very closely with whoever the nominee is," he says of the DCCC, which organizes fundraising and strategy for the House elections. "In the interest of making sure that our members are in a strong position going forward, I have not gotten involved."
Democratic State Chairman Michael Cryor and Vice Chairwoman Lauren Glover also remain neutral, as does state Del. Heather R. Mizeur, who is a member of the Democratic National Committee.
"I've always seen my role as a DNC member to be a cheerleader for the party and all of its candidates and to get people excited about the campaigns," Mizeur, a Montgomery County Democrat, says.
She says the campaigns have been calling since last March or April.
"Most of the outreach has been at the Clinton and Obama level," Mizeur says. "I'm staying neutral right now."