Democrat Hillary Clinton pumped new life into her presidential campaign Tuesday with decisive primary wins in Ohio, Texas and Rhode Island. Rival Barack Obama continues to lead in the delegate count, but Clinton's victories mean that the battle for the Democratic Party's presidential nomination will go on for weeks, if not months. VOA national correspondent Jim Malone reports from Washington.

Hillary Clinton told U.S. television networks that her three victories Tuesday back up her claim that experience makes her the stronger Democratic candidate for president.

"Voters are finally focused on who they think would be the best commander in chief and who would be the best president to turn this economy around," said Clinton.

Clinton appeared on NBC's Today program, as did rival Barack Obama.

Obama won only one of the four primary contests on Tuesday, finishing first in Vermont.

Despite Clinton's victories, Obama noted that he maintains his lead in delegates and remains on track to win the party nomination.

"The bottom line is that we are in a very strong position," said Obama. "Senator Clinton barely dented the delegate count Tuesday. We are going on to Mississippi and Wyoming where we feel confident that we can do well, and this process is ultimately going to be about who has got the most delegates and we think we will be in that position.

Even though Obama remains in the lead in the delegate count, it is unlikely that either Democrat will win enough delegates in the remaining caucuses and primaries to secure the nomination outright before the party's national nominating convention in Denver in late August.

That means both candidates will appeal to the roughly 800 super delegates for support. Super delegates are elected officials and party activists who are invited to the national convention as uncommitted delegates, meaning they can support whomever they want.

Clinton argued on NBC that her attacks on Obama have raised questions about whether he would be the strongest Democrat in a general election campaign against the presumed Republican nominee, Senator John McCain of Arizona.

"People are super delegates for a purpose," she said. "They are to exercise independent judgment and it is very important that they exercise that judgment based on what they believe will lead to the best nominee."

Political experts say Clinton's late attacks on Obama raising questions about his ability to handle national security issues may have tipped the balance in Clinton's favor in Ohio and Texas.

"There was clear momentum for Hillary Clinton in the Democratic primaries," said Leoni Huddy, an expert on political polling and a consultant for CBS News. "She won votes from people who had made up their mind in the last week, about 30 percent of all voters. In Texas, 21 percent made up their mind in the last three days, and 61 percent voted for Clinton."

Experts believe that Clinton's victories on Tuesday will keep the Democratic race going indefinitely.

John Fortier, an analyst at the American Enterprise Institute in Washington, says a number of uncommitted super delegates who had been leaning toward Obama before Tuesday's results are likely to hold off for now.

"Hillary Clinton is hoping that Tuesday's results will stanch that flow and that she may even be able to get a few pledges herself," he said. If she can do that and she can hold her own and be alive and do well in Pennsylvania in late April that is her chance to climb back into this race. If the super delegates, on the other hand, keep slowly going towards Obama because they think he is the nominee, that is going to make Tuesday's win seem insignificant because the delegate count will go right back to what it was."

Obama seems in a favorable position in the next two contests on the Democratic side, Saturday's caucus in Wyoming and next Tuesday's primary in Mississippi. But Clinton is favored in the next big state primary when Pennsylvania votes on April 22.

In the Republican race, Senator John McCain's sweep of the four Tuesday primaries clinched his party's nomination.

McCain went to the White House Wednesday where he was formally endorsed by President Bush.

"And there is still an enemy that lurks, an enemy that wants to strike us, and this country better have somebody in that Oval Office who understands those stakes, and John McCain understands those stakes," said President Bush.

McCain says he is looking forward to running in the general election campaign no matter who emerges as the Democratic nominee.

"A respectful campaign based on the issues and based on the stark differences and vision that we have for the future of America," he said.

McCain will be formally confirmed as the party nominee at the Republican Party's national nominating convention in early September in Minneapolis-St. Paul.