In the last day before what has come to be known as Super Tuesday II, Barack Obama and Hillary Clinton are making their central pitch to Democratic primary voters in the Lone Star and Buckeye states over who is the best candidate to lead the nation.

Ohio and Texas voters are in the position to decide the long, hard-fought Democratic presidential primary race, and both candidates are trying to paint themselves to voters as the most battle-ready, whether on the economy or national security.

With Clinton’s future becoming ever more contingent on her showing in Ohio and Texas as well as smaller states Rhode Island and Vermont, which also vote on Tuesday, her campaign is following up on an implied pledge to throw everything but the kitchen sink at Obama.

In just the past few days, Obama has faced stepped-up assaults over his supposed discussions with Canadian leaders about the North American Free Trade Agreement, his ties to land developer Tony Rezko and his leadership of a Senate Foreign Relations subcommittee that had oversight of some operations relating to Afghanistan.

Clinton even raised eyebrows during an appearance on CBS’ “60 Minutes” Sunday night when she qualified her dismissal of rumors that Obama is lying about his religion, and is secretly Muslim, not Christian. Obama has repeatedly call the rumor a “systematic e-mail smear campaign” deliberately generated to discredit him and build prejudice against Muslims.

“You know, I take him on the basis of what he says and, you know, there isn’t any reason to doubt that,” Clinton said of the rumors, adding that she’s sympathetic to anyone systematically targeted. “There is nothing to base that on, as far as I know.”

Questions over who is better qualified to manage national security matters dominated weekend campaigning after Clinton’s campaign released an ad on Friday asking voters who they trust to respond to a crisis delivered in a 3 a.m. phone call.”It took a Clinton to clean up after the first Bush, and it’s going to take a Clinton to clean up after the second Bush,” Clinton told a Toledo, Ohio, audience Monday to a round of cheers. “Because President Bush is just going to leave this big mess for his successor. You know, we’ve got two wars going on. We’ve got to end the war in Iraq and win the war in Afghanistan and go after the people, and bring ‘em to justice, who attacked us.”

Clinton is also hitting on the issues of international trade and the economy — especially in Ohio, which has been hard-hit by the housing market collapse and persistent manufacturing job losses to foreign competitors. She said it’s disingenuous for Obama to “send out misleading and false information” about her position on NAFTA while at the same time giving the Canadians “the old wink, wink” about his own criticisms of the trade deal.

“It raises questions about Senator Obama coming to Ohio and giving speeches against NAFTA,” she siad.

For his part, Obama has been fending off the onslaught, and even stepped up his own attacks on Clinton, saying the New York senator failed to read the key National Intelligence Estimate before she voted to authorize the use of force in Iraq in 2002. He also blasted Clinton on the theme of readiness.

“What precise foreign-policy experience is she claiming that makes her qualified to answer that telephone call at 3 a.m. in the morning?” Obama asked Sunday. “When it came time to make the most important foreign policy decision of our generation the decision to invade Iraq, Senator Clinton got it wrong.”

One of the large labor unions endorsing Obama also called out Clinton for criticizing Obama’s position on NAFTA.

“We are disappointed that the Clinton campaign has decided to peddle a memo from a low level bureaucrat of an anti-worker Canadian administration that is in complete contradiction to the actual positions of Senator Obama,” officials from the Change to Win leadership said in a joint statement released Monday. “Our members should remember that it was the Clinton administration that was the driving force behind the passage of NAFTA in 1993 and its aggressive campaign for NAFTA is a big reason the Democrats lost the House in 1994.”

Vowing to Go On

Even as more and more Democrats, including Clinton’s own advisers and husband, indicate that the race will be over if she doesn’t win in Ohio and Texas, Clinton’s camp is vowing to go on, arguing that the new light on Obama is starting to emit heat.

The campaign will be likely “to enter an interesting phase” after Super Tuesday II, said Communications Director Howard Wolfson. With six weeks to go until Pennsylvania’s April 22 primary, which follow the post March 4 week’s smaller contests in Wyoming and Mississippi, plenty of time is available for exploring and scrutinizing Obama’s record with Rezko and exactly what Obama’s advisers discussed with the Canadians about NAFTA.

“We feel the longer this goes … the better it is for us,” said Clinton adviser Doug Hattaway. Hattaway suggested that the more the Clinton campaign keeps up the one-two punch of the economy and national security, the better the senator does and the more Democrats she will win over.

The campaign has reached a “tipping point,” added senior adviser Mark Penn, who argued Monday that momentum has shifted in Clinton’s direction. He was unable, however, to point to polling data to support this contention.

Clinton has continued to cede ground in Texas and Ohio to Obama. In Texas she once held a strong lead but now trails him in statewide polls. And in Ohio, Clinton’s once wide margin has dwindled, and according to some polls, disappeared.

In a new Feb. 21-29 Columbus Dispatch poll of 2,308 registered Democrats, Clinton leads Obama by 16 points ahead of Tuesday’s showdown, 56-40. But the poll also showed that state Democrats might not hold their support for her past this week. Fifty-six percent of respondents told the Dispatch that Obama will win in November compared to 30 percent who said they think Clinton would.

Other polls show Clinton’s lead slimmer: A Feb. 26-28 FOX News/Opinion Dynamics poll showed her lead at 8 points; a Sunday Rasmussen Reports poll shows Clinton’s lead at 6 percent; A March 1-2 Suffolk University poll shows her lead at 12 points; and both a Feb. 27-March 2 Quinnipiac University and a Feb. 27-29 Cleveland Plain Dealer poll showed her lead at 4 percent — just outside the Qunnipiac poll’s margin of error, but inside the Plain Dealer’s range of statistical error.

A Feb. 29-March 2 Reuters/C-SPAN/Zogby poll places Obama 2 percentage points ahead of Clinton, a statistical tie in the poll of 761 likely voters, which had a 3.6-percentage point margin of error.

Clinton began her day Monday with a 5 a.m. ET event at a Chrysler plant in Ohio, and then made the rounds on network morning shows before holding a rally in Toledo. She was off to Texas for two rallies and a town-hall meeting in Beaumont and Austin before planning to return Tuesday to Ohio, and watch election returns in Columbus.

Obama was spending his day in the Lone Star State, attending a town-hall meeting with veterans in San Antonio, and then a Carollton event at a high school. He was to end his day with a rally at the Houston convention center.

Obama holds a slim lead in Texas polls heading into Tuesday’s balloting. The Feb. 26-28 FOX News poll put Obama ahead of Clinton by 3 points — within the 4-point margin of error. The Reuters/Zogby/C-SPAN poll also puts Obama ahead by 3 points. A WFAA/Belo tracking poll showed then tied at 46 percent.

While repeating the mantra that voters may experience “buyer’s remorse” once they learn more about Obama, Wolfson sounded opaque on Clinton’s future if she doesn’t win Texas and Ohio.

“If we don’t (win), well we’ll talk about that (the future) then,” he said.

FOX News’ Major Garrett, Steve Brown and Aaron Bruns contributed to this report.