(CNN) -- A string of recent victories and endorsements from key party insiders have Democratic presidential hopefuls Barack Obama and Hillary Clinton running neck-and-neck in the increasingly important battle for delegates.
Sens. Hillary Clinton and Barack Obama are running a tight race for Democratic delegates.
Clinton holds a narrow 27-delegate lead over Obama, 1,148 to 1,121, down from her lead of more than 100 delegates a month ago, according to CNN's estimate.
A candidate must secure the support of 2,025 delegates to clinch the Democratic presidential nomination.
In the Republican race, Arizona Sen. John McCain maintains a comfortable lead in delegates over his main rival Mike Huckabee, despite the former Arkansas governor's wins Saturday in Kansas and Louisiana and a strong showing in Washington state.
Obama's surge in delegates is due primarily to his electoral victories on Super Tuesday and in contests held over the weekend, including Sunday's Democratic caucuses in Maine, which he won by a comfortable margin.
The first-term Illinois senator won at least 923 delegates from those contests, compared with at least 876 delegates for Clinton, according to CNN's analysis of voting results.
Another 67 delegates from those races still remain unallocated in areas with particularly tight vote results or local delays in vote-counting. But 60 of those slots are in states Obama won, which may give him the edge as these remaining delegates are allocated.
Overall, Obama has won 986 delegates from contests this year, compared to 924 for Clinton.
CNN's delegate estimate includes both delegates won in primaries and caucuses as well as preferences of so-called "superdelegates," a group of almost 800 Democratic party officials and leaders who also will cast votes at the nominating convention this summer.
Because superdelegates are not required to make their presidential preferences public and are free to change their minds, it is difficult to pinpoint the exact number of superdelegate supporters either candidate has at any given time.
CNN estimates, however, that Clinton has the support of at least 224 superdelegates compared with at least 135 superdelegates for Obama, according to an ongoing survey. The remaining 400 or so superdelegates either remain neutral, undecided or have not publicly revealed their preferences.
Though Clinton appears to hold a sizable lead among these Democratic officials, Obama has scored a series of high-profile superdelegate endorsements in recent weeks, including nods from Sens. Ted Kennedy and John Kerry of Massachusetts.
Democratic superdelegate Sam Spencer said he's not entirely comfortable with the decisive role superdelegates could play in this election.
"I think the best people to decide who our nominee should be ... should be actual voters in primaries and caucuses," Spencer said on CNN's "American Morning." "I think superdelegates are somewhat outdated, and it's not the most democratic way of doing things."
Nancy Larson, another Democratic superdelegate, said she hopes a decision gets made "before we have to step in."
"They never anticipated that we would have two superstars locked in a dead heat, so I think there is no playbook for this," she said.
On the Republican side, McCain leads the shrinking GOP field with 723 delegates to 217 for Huckabee and 16 for Texas Rep. Ron Paul.
Former Massachusetts Gov. Mitt Romney suspended his campaign after Super Tuesday, but still retains the 286 delegates he won in primaries and caucuses.
Though the national Republican Party does not have superdelegates, 123 members of the Republican National Committee are free to vote for any candidate at the GOP convention this summer in Minneapolis, Minnesota. Of those, 26 support McCain and three support Huckabee.
A total of 1,191 delegates are needed to win the GOP presidential nomination.