If a Democrat wins a primary in a Republican stronghold, is it really a win? That is the question Clinton supporters will be posing to superdelegates in the coming weeks.

With neither Democratic presidential candidate likely to reach the number of pledged delegates required to secure the nomination, the Clinton campaign is relying on its argument that victories in big states such as California and Ohio make Sen. Hillary Clinton a stronger candidate to defeat presumptive Republican nominee Sen. John McCain.

Clinton aides are highlighting that Sen. Barack Obama has won among affluent voters in caucuses and primaries in states with small populations of Democrats -- such as Idaho and Wyoming -- and among African Americans in Republican states unlikely to turn blue in November -- such as South Carolina and Georgia.

A Clinton campaign memo released early this month noted Sen. Obama has won 10 out of the 11 core Republican states that have held primaries or caucuses this year. Wyoming, for one, the campaign later noted, hasn't voted for a Democratic presidential candidate since 1964.

Obama campaign manager David Plouffe has rejected the Clinton campaign's attempts to give greater importance to certain states and notes that Sen. Obama won Missouri and Illinois, two large swing states.

The Clinton campaign has been using the big-state argument on and off since Super Tuesday, when Sen. Clinton won big prizes including New York, California and New Jersey. The argument has been central to the campaign since her Ohio and Texas victories, and Clinton aides will be aggressively pushing the point in the weeks before the Pennsylvania primary on April 22.

Pennsylvania represents another battleground state for the Democrats in November. A recent poll of likely voters conducted by SurveyUSA puts Sen. Clinton ahead in the Keystone State, with 55% favoring her compared with 36% favoring Sen. Obama. Other polls give her a narrower lead.

"I think it is significant that I have won Ohio and I won Florida and I've won the big states that serve as those anchors on the electoral map," Sen. Clinton told reporters on board the campaign plane in Scranton, Pa.

Monday in Philadelphia, Sen. Clinton is expected to deliver a speech addressing the housing crisis followed by an event to reach women voters.

The Clinton campaign also has been making an aggressive push for primaries in Michigan and Florida to be counted or redone. Both states were stripped of their delegates to the Democratic National Convention after staging contests earlier than party rules allowed. Last week, Michigan Democrats rejected the idea of a vote-by-mail presidential primary to replace the January vote and were unable to agree to a bill that would authorize a state-run, privately funded primary. Florida also has ruled out a revote.

Clinton adviser Harold Ickes says a revote would prove Sen. Clinton can win in the big, swing states that are important in a general election.

But even if Sen. Clinton won revotes in Michigan and Florida, she would probably still lag in the delegate count. Sen. Obama leads the delegate race with 1,620 to Sen. Clinton's 1,499, including superdelegates, according to the Associated Press; roughly 2,025 are needed to secure the nomination.

Sen. Obama also leads in the money race, with $32 million on hand at the end of February compared with Sen. Clinton's $11 million, according to the latest financial reports filed with the Federal Election Commission.

A Gallup tracking poll conducted last week shows Sen. Obama leading nationally with 48% of the vote compared with 45% for Sen. Clinton. Other polls show Sen. Clinton slightly ahead nationally.

Historians and political pundits caution that victories in a primary don't necessarily produce dividends in a general election.

"She can win every Democratic vote in the world [during the primary] and not win a general election," says Peter Brown, assistant director of the Quinnipiac University Polling Institute. He points to the small segment of more liberal Democrats who participate in a primary compared to the huge cross section of voters likely to turn out in a general election.

Sen. Clinton won Ohio, for example, with 54% of the vote, compared with 44% for Sen. Obama. But a recent Rasmussen poll of likely voters projected her losing Ohio to Sen. McCain in a general election, 46% to 40%. The poll showed Sen. McCain defeating Sen. Obama in the state by the same margin; 14% of respondents said they were undecided.

Allan Lichtman, a political historian at American University, says a candidate's primary showing has very little to do with the general-election result. "The argument holds no water at all, not even a thimbleful," Mr. Lichtman says. He points to the 1980 primary, when incumbent Democrat Jimmy Carter carried most of the big swing states, and early polls predicted he would defeat Republican Ronald Reagan in the general election by as much as 25 percentage points. Instead, Mr. Reagan decisively captured the White House. Former Massachusetts Gov. Michael Dukakis and Massachusetts Sen. John Kerry racked up primary victories in key swing states in 1988 and 2004, respectively, only to then lose those states to Republicans.

The Clinton campaign says that just because Sen. Clinton has won in the big states in the primary doesn't mean Sen. Obama will lose those states in a general election. "Nobody is saying Barack Obama will definitely lose Pennsylvania in the fall," says that state's governor, Ed Rendell, a Clinton backer. "If Sen. Obama is the nominee, we will work our hearts out for him...but we are much more confident we would win with Sen. Clinton."

The campaign also argues that big states typically have primaries rather than caucuses, and that primaries are more reflective of the results of a general election.

Part of the reason Sen. Clinton has done well in larger states is strategy. The campaign chose to pour limited resources into advertisements and field offices in delegate-rich Ohio and Texas, rather than make a big push in small caucus states where Sen. Obama was favored.

Sen. Clinton's wins also reflect her solid base of support among Catholics, working-class white voters and Hispanics, three important swing groups for the Democrats to capture in November.

Sen. Obama rejects the notion that he has failed to attract a broad coalition of voters important to the party. "In South Carolina, where the Confederate flag still flies, we built a powerful coalition of African Americans and white Americans," he said in a speech last week.

On Friday, Sen. Obama picked up the endorsement of former presidential candidate and New Mexico Gov. Bill Richardson. Gov. Richardson, a Mexican-American, could help Sen. Obama broaden his appeal among Hispanics.

Write to Amy Chozick at amy.chozick@wsj.com