HAMMOND, Ind. (AP) — If Hillary Rodham Clinton is feeling heat from pundits and party elders to quit the race and back Barack Obama, you'd never know it from her crowds, energy level and upbeat demeanor on the campaign trail.

"There are millions of reasons to continue this race: people in Pennsylvania, Indiana and North Carolina, and all of the contests yet to come," Clinton told reporters Friday. "This is a very close race and clearly I believe strongly that everyone should have their voices heard and their votes counted."

The former first lady weathered a two-pronged blow Friday, with influential Pennsylvania Sen. Bob Casey Jr. endorsing Obama and another Senate colleague, Vermont Democrat Patrick Leahy, urging her to step aside. But to hear Clinton tell it, it was just another day in an epic primary battle whose result is still not known.

"I believe a spirited contest is good for the Democratic Party and will strengthen the eventual nominee," she said. "We will have a united party behind whomever that nominee is. ... I look forward to campaigning over the next several months."

Traveling across Indiana, the former first lady was greeted by large, enthusiastic audiences who roared their approval at her proposals to help fix the state's economic challenges.

At events here and in North Carolina on Thursday, Clinton raised the issue of whether she should quit the race, only to have it firmly batted down by her supporters.

"There are some people who are saying, you know, we really ought to end this primary, we just ought to shut it down," she said in Mishawaka, Ind., drawing cries of "No, no!" inside a packed gymnasium.

In Hammond, she compared the state's struggling steel industry to her own efforts to fight the odds.

"I know a little bit about comebacks," she said to cheers. "I know what it's like to be counted down and counted out. But I also know there is nothing that will keep us down if we are determined to keep on."

Yet despite the optimistic talk, there is no doubt that Clinton faces an uphill battle to secure securing her party's nod.

She trails Obama among pledged delegates and is not expected to close that gap even with a strong showing in the 10 remaining primaries. She also trails in the popular vote and probably cannot make up the deficit without revotes in Michigan and Florida, whose January primary results were nullified because they broke party rules. Neither state is expected to go through with new contests.

As a result, the so-called "superdelegates" — some 800 elected officials and party insiders who can choose to support any candidate — would risk intraparty rebellion if they backed Clinton.

The New York senator reaffirmed her belief that superdelegates will base their choice on which candidate would make the best president and would have the best chance to beat Republican John McCain in November.

All the more reason to look forward to Pennsylvania's primary April 22, Indiana and North Carolina's May 6 and the handful of others that follow, Clinton insisted.

"There will be additional information that will inform those decisions that will come from these upcoming contests," she said.

Dismissing concerns raised by Democratic National Committee Chairman Howard Dean that a prolonged contest would demoralize the party base, Clinton pointed to a recent surge in voter registration and projected turnout in Pennsylvania. Democratic registration went up by 4 percent in the state this year, while it declined 1 percent among Republicans.

"Both Senator Obama and I have brought millions of new people into the process," she said. "People are registering to vote for him and to vote for me. They're part now of the Democratic Party."

Asked what she thought of Obama's comment Friday that the Democratic primary race resembled "a good movie that lasted about a half-hour too long," Clinton smiled broadly and said, "I like long movies."