Now that presidential candidate Hillary Clinton has won primaries in Ohio and Texas, the scene is set for perhaps a protracted campaign that could end in August with a fierce, unprecedented battle for the Democratic nomination.

"There's no doubt that Sen. Clinton went very negative over the last week," Obama told reporters Wednesday. He said the Clinton campaign's multiple attacks "had some impact" on the election results, "particularly in the context where many of you in the press corps had been persuaded that you had been too hard on her and too soft on me."

Clinton, who stopped Obama’s 12-primary winning streak Tuesday, is already laying claim that as the candidate who has won Ohio and more big states, she should be crowned with the Democratic nomination.

But the Obama camp says simply this: Do the math.

Even if Clinton wins every contest left, she would still have a difficult time overcoming Obama's pledged delegate lead because there are not enough pledged delegates left to secure.

In the overall race for the nomination, Obama has 1,562 delegates. Clinton has 1,461. It takes 2,025 delegates to secure the Democratic nomination. In Tuesday's contests, Clinton won at least 185 delegates, and Obama won at least 173 -- a net gain of eight delegates for Clinton.

"The problem for her is delegate math," Colorado state Sen. Peter C. Groff, publisher of Blackpolicy.org and executive director of the Center for African-American Policy at the University of Denver, told BlackAmericaWeb.com Wednesday. "Obama is still ahead in delegates, and she can't catch him unless she wins every single contest to follow with a 65 - 35 percent margin."

Clinton’s hard-hitting ads about Obama clearly resonated with many voters in Ohio and Texas, and Democrats are already urging Obama to go after Clinton with more intensity and shed the ‘Mr. Nice Guy’ image during debates.

Obama told reporters that he planned to do more in the days ahead to raise doubts about Clinton's claims to foreign policy and other Washington experience. In a television ad that her campaign credits with helping her win, she portrayed herself as most prepared to handle an international crisis.

"What exactly is this foreign policy experience?" Obama asked. "Was she negotiating treaties? Was she handling crises? The answer is no."

But tough talk may have its consequences, and race could play a role in Obama’s campaign strategy, Groff says.

"Obama has a hard choice to make," Groff said. "He must decide if he too can sling some mud; the trick is how he does that without getting dirty."

"He has to walk his talk and hang tight on the the line of this 'new politics' approach he's been pushing, the new school of thought where you are above the fray and focused on the issues without getting bogged down in petty campaign tricks," he added. "But, how does he attack a woman? And how does he do it as a black man attacking a white woman? It will be a very compelling balancing act he'll have to play."

Neither candidate is likely to get the 2,025 delegates needed to secure the nomination by August, so the Obama camp’s strategy is this: If Obama has the most delegates by August, then he should become the Democratic nominee.

"We have nearly the same delegate lead as we did this morning, and we are on our way to winning this nomination," Obama told supporters Tuesday night.

Clinton’s strategy, some political observers say, is to perhaps circumvent the system and perhaps ask superdelegates to go against the will of voters should Obama end up with more delegates by August. For Clinton, this move could alienate members in her party, some of whom already believe that she is not willing to play by the rules.

And she could also seek to influence delegates from Michigan and Florida who were disenfranchised early in the primary process.

Next up: Wisconsin Saturday and Mississippi Tuesday. Either Clinton or Obama will have to harness the toughness to take on GOP nominee Sen. John McCain in the November general election.

Obama Texas State Director Adrian Saenz issued a statement Wednesday on the projected primary and caucus results that showed Obama won five more Texas delegates than Sen. Clinton, despite her winning the popular vote.

“By fighting the primary to a near-draw and earning a resounding victory in the caucus, the people of Texas have moved Barack Obama one step closer to claiming the Democratic nomination for president,” Saenz said. 

For now, some Democrats say Obama must talk about his strengths on foreign policy issues; he has to lay out a clear economic plan moving into Pennsylvania, and he has to speak more about Bill Clinton supporting NAFTA when he was president.

They also say Obama must to build a solid case that Hillary Clinton has no more real experience than he does: In fairness, both candidates have not run anything more than their Senate offices and their presidential campaigns, so neither can lay claim to governing experience.

"If Sen. Clinton had lost Ohio and Texas, her bid for the Democratic nomination would have ended," Michelle Bernard, a black conservative and president of the Washington, D.C.-based Independent Women’s Voice, told BlackAmericaWeb.com Wednesday.

"Many analysts believe that it is mathematically impossible for Senator Clinton to gain more pledged delegates than Senator Obama," said Bernard. "That being said, there are not enough pledged delegates remaining for either candidate to win the Democratic nomination based upon these delegates alone. The 2008 Democratic nominee will be selected by the party’s superdelegates."

Meanwhile on Wednesday, Obama picked up an endorsement from Dayton Mayor Rhine McLin, an African-American superdelegate. McLin said she will wait to hear from her constituents to decide how to use her superdelegate vote. It was not clear why McLin waited until after the Ohio primary to announce her endorsement.

Also on Wednesday, the Obama campaign released a terse statement calling on Clinton to release her tax returns.

"In the face of her unwillingness to release her tax returns, Hillary Clinton has made the false case in this campaign that she is more electable because she has been fully vetted," the statement said.

"When it comes to her personal finances, Senator Clinton’s refusal to release her taxes returns denies the media and the American people the opportunity to even begin that process. Though her campaign has tried to kick the issue down the road, Democratic voters deserve to know, right now, why it is she is hiding the information in her tax returns from last year."

The Clinton camp fired back immediately.

"Faced with many legitimate questions about Senator Obama's long-time relationship with indicted political fixer Tony Rezko, the Obama campaign has chosen to lash out at Senator Clinton. Here are the facts: Over 20 years of the Clintons' tax returns are in the public domain. Their tax returns since they left the White House will be made available on or around April 15. This information will be in addition to 15 years of uninterrupted public financial disclosure reports," the statement said.

"Democratic members need to get ready; the show is about to begin," Craig Kirby, a Democratic political strategist, told BlackAmericaWeb.com. "We are really about to see what Barack is made of and what fight he has in him." 

"Clinton has to be very careful not to get too arrogant in the wake of these wins," Groff said. "She's got a long way to go still, and if she becomes too dismissive and arrogant, she'll risk turning off many Pennsylvania voters."

"There was a confluence of factors helping her -- a tipping point of events" -- from the infamous Farrakhan question and '3 a.m.' ad to the strangely timed photo of Obama in Somali garb to the reports about Obama's economic advisor meeting with the Canadian embassy on NAFTA," said Groff. "These were all carefully laced with a volatile mix of racial, religious and protectionist code that tapped into the insecurities of working class white voters and white female security moms."

Donna Brazile, a Democratic strategist and superdelegate, said Howard Dean, chairman of the Democratic National Committee, should be prepared to step in to negotiate the process should the attacks and negative campaigning intensify.

And now that Clinton won the Ohio and Texas primaries, she’s talking about the potential for Obama to become her running mate in the presidential election McCain.

Asked on CBS's "The Early Show" whether she and Obama should be on the same ticket, Clinton said, "That may be where this is headed, but of course we have to decide who is on the top of ticket. I think the people of Ohio very clearly said that it should be me."

Like it or not, Democrats are in for a longer –- and perhaps more bruising -- campaign that may not yield a nominee until the national convention in August.

"The problem for Sen. Obama at this stage is perception and momentum," Groff told BlackAmericaWeb.com. "She made him look more like a politician than the movement he had become. She deflated his iconic status, to a degree. So, he has no choice but to win Wyoming and Mississippi. He then has six weeks to turn Pennsylvania into Iowa."