NEW YORK (Reuters) - Democratic candidate Hillary Clinton ridiculed rival Barack Obama as all talk and little substance on Wednesday, trying to slow the momentum that has given him 10 straight victories in the race for the party’s U.S. presidential nomination.

The New York senator and former first lady sharpened her attack on Obama ahead of the March 4 Democratic contests in Texas and Ohio, which have become critical to her presidential aspirations following her losses on Tuesday to Obama in Wisconsin and Hawaii.

But support for the first-term Illinois senator, whose powerful “yes we can” speaking style has propelled him to the front-runner’s position, continued to mount, with the 1.25 million member Teamsters union formally endorsing him on Wednesday.

His long string of victories put Clinton in the awkward position of telling supporters, in media interviews and speeches, “Don’t give up on this!” and “This campaign goes on!” while her aides explained how she would close the gap with Obama by the time of the Puerto Rico contest in June.

But Obama has used his string of victories to broaden his voting coalition and has taken control of the race to decide the Democratic nominee for the November election. He has wins in 25 of the state-by-state contests while Clinton has 11, and he has begun to erode support among her core base of women.

At a fund-raising event in New York, Clinton belittled Obama as an inexperienced choice for commander-in-chief in a dangerous world, for advocating a health care plan that is not as expansive as hers and for giving airy speeches.

“It’s about picking a president who relies not just on words but on work, on hard work,” she said. “We need to make a choice between speeches and solutions, because while words matter greatly, the greatest words in the world are not enough unless you match them with action.”

“Now others might be joining a movement,” she said. “Well, I’m joining you on the night shift, and on the day shift.”

Obama rejected her criticisms while campaigning in Texas, telling a crowd of some 17,000 in Dallas Clinton was right that the race was about choices but wrong about everything else.

“Contrary to what she’s been saying, it’s not a choice between speeches and solutions,” he said.

“It’s a choice between a politics that offers more of the same divisions and distractions that didn’t work in South Carolina and didn’t work in Wisconsin and will not work in Texas. Or a politics of common sense, of common purpose, of shared sacrifice and shared prosperity.”

BUILDING A NATIONAL LEAD

Underscoring Clinton’s high negative ratings in public opinion polls, he added: “It’s a choice between going into the general election with Republicans and independents already united against us or running with a campaign that has already united Americans of all parties around the agenda for change. That’s the choice.”

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Clinton was asked about a controversy involving Obama’s wife, Michelle, who said in Wisconsin this week she felt pride in the United States for the first time in her adult life because it felt like hope was returning to the nation.

The former first lady, questioned about the remark, did not criticize Michelle Obama’s comment but said: “I think we’ve all been disappointed in our country, but I’ve been proud of America on many occasions during my lifetime.”

She cited the fall of the Soviet Union and the Berlin Wall, advances in the United States on voting rights and civil rights and some accomplishments during her husband’s presidency, such as his work to stop ethnic cleansing in Kosovo.

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A new Reuters/Zogby poll released on Wednesday indicated Obama has leaped past Clinton and built a big national lead in the U.S. Democratic presidential race.

The poll showed Obama, who would be the first black president, with a 14-point edge over Clinton, 52 percent to 38 percent, after being in a statistical tie with the New York senator last month.

Clinton was flying to Texas for events in Hidalgo and Brownsville before a Thursday night debate in Austin with Obama that is one of her last chances to take him on face-to-face.

Analysts believe she can only turn around her campaign by winning big victories in two weeks in Texas and Ohio.

The two states offer a rich trove of 334 delegates to the Democratic nominating convention this summer, giving Clinton the chance to catch up with Obama after falling behind in the delegate count.

Obama and the likely Republican nominee, Arizona Sen. John McCain, were already tossing barbs at each other in what could be a preview of the general election campaign.

In Wisconsin on Tuesday night, McCain asked: “Will we risk the confused leadership of an inexperienced candidate?”

Obama fired back that McCain backed President George W. Bush’s economic policies and wants to keep U.S. troops in Iraq indefinitely, while he would withdraw them quickly.

(Additional reporting by John Whitesides, Jason Szep, Jeff Mason and Donna Smith, writing by David Alexander, editing by Todd Eastham)