WASHINGTON (CNN) -- Three days after Sen. Hillary Clinton's win in Pennsylvania, a new CNN "poll of polls" shows a dead heat in Indiana ahead of the May 6 primary, the next crucial battleground that could decide the Democratic presidential nomination.
Sen. Hillary Clinton campaigns this week in Indianapolis. Her supporters say she needs to carry Indiana on May 6.
Sen. Barack Obama is tied with Clinton at 45 percent, with 10 percent of respondents unsure, according to the Indiana Democratic poll, an average of campaign surveys.
The poll of polls consists of three surveys: Research 2000 (April 23-24), ARG (April 23-24), and The Indianapolis Star (April 20-23). All polls include interviews conducted after the Pennsylvania primary, which Clinton won Tuesday by about 55 percent to 45 percent.
The Research 2000 poll released Friday showed Obama leading Clinton by 1 percentage point, 48 percent to 47 percent. The candidates are statistically tied given that poll's margin of error of plus or minus 5 percent.
The survey also shows both candidates are strong with constituencies that backed them in other states: Clinton easily wins among senior citizens and women, while Obama has the advantage with young voters.
With the campaign settled into a seemingly endless slugfest, roughly two-thirds of people in a separate survey done by the Pew Research Center said the race has gone on "too long."
Half of those polled said the campaign has become "too negative." And the candidates aren't the only ones fighting fatigue: More than a third said the closest race in a generation is "too dull."
Two months ago, 28 percent of voters in the same survey said the race was too negative, and one in four said it was too dull.
The unresolved contest also seems to be leaving Democrats feeling a little shell-shocked. Two months ago, roughly one in five Democrats thought the campaign was too negative, but the number now has risen to 50 percent, according to the Pew survey. Watch CNN's Candy Crowley on the Democrats' race to the finish line »
With nine primaries left before June 3, Indiana and North Carolina are the next front in the Democratic nomination fight. The May 6 contests have 187 combined delegates at stake.
Clinton's advisers appear to be focusing most efforts on Indiana, a state with lunch-bucket demographics that have proven friendlier to the former first lady. Indiana has 72 delegates.
One of Clinton's strongest supporters calls the state a "must win" for the senator from New York.
"I think it's going to be very difficult for Sen. Clinton if she loses both in Indiana and North Carolina," James Carville said Wednesday on CNN's "Larry King Live."
"If she wins in Indiana, it's going to cause some people to turn up and look around. I think it's a very important contest."
Clinton was in North Carolina early Friday, campaigning in Jacksonville, before heading to Indiana for events in Bloomington, Gary and East Chicago.
Obama has a significant lead in the polls in North Carolina and is heavily favored to win there.
Obama owes his victories throughout the nomination battle to African-Americans, young voters, upscale whites and independent voters.
Those voters come in bunches in North Carolina, and their ranks are growing.
Since the beginning of January, nearly 65,000 new voters between the ages of 18 and 24 have registered in the state as Democrats or unaffiliated voters. More than 67,000 new African-American voters have registered over the same period.
African-Americans are expected to make up around 40 percent of the primary electorate, giving Obama a healthy starting point in his chase for a large share of the state's 115 pledged delegates.
Obama is likely to capture votes in the Research Triangle, a thriving swath of counties in and around the Raleigh-Durham area filled with highly educated tech workers and medical researchers.
Clinton advisers acknowledge the tall odds there.
Clinton campaign Chairman Terry McAuliffe said earlier this week he sees North Carolina as "competitive," but the campaign's state director, Ace Smith, already has lowered expectations, saying he sees no chance for a victory.
At an event last week in Winston-Salem, Smith said a Clinton win in North Carolina "would be the biggest upset of the century."
Meanwhile, House Speaker Nancy Pelosi, D-California, made it clear Thursday that she thinks Clinton and Obama shouldn't run on a joint ticket this fall.
"I don't think it's a good idea," she said on "Larry King Live." "First of all, the candidate, whoever he or she may be, should choose his or her own vice presidential candidate. I think that's appropriate. That's where you would see the comfort level, not only how to run but how to govern the country.
"And there's plenty of talent to go around to draw upon for a good, strong ticket. I'm not one of those who thinks that that's a good ticket." Watch as Pelosi predicts one of the Democrats will be president » E-mail to a friend
CNN's Peter Hamby, Rebecca Sinderbrand, Alexander Mooney and Ed Hornick contributed to this report.