CHARLOTTE, North Carolina (Reuters) - Locked in one of the costliest and most consequential statewide contests in the country, Elizabeth Warren largely ignored her own campaign Wednesday night to paint President Barack Obama as a populist up against a Republican who has sided with plutocrats.

A candidate for the U.S. Senate in Massachusetts, Warren was chosen by the Democratic Party to appear on national television at the party's convention to describe what she said were Obama's efforts to level the playing field for the American middle class.

Warren criticized Republican challenger Mitt Romney's often ridiculed statement that "corporations are people."

"No, Governor Romney, corporations are not people," Warren said. "People have hearts, they have kids, they get jobs, they get sick, they cry, they dance. They live, they love, and they die. And that matters."

A victory over Sen. Scott Brown on November 6 would aid a Democratic Party that risks losing its majority in the Senate. It would also provide a symbolic lift for Democrats, returning to them the seat that was held by liberal stalwart Edward Kennedy for five decades.

Throughout her campaign, Warren has tried to use Romney's record as a roadblock to Brown's re-election, hoping to link the freshman senator, who boasts of his moderate views, to the more conservative positions of Romney and the Republican Party.

Warren has given voice to a populist economic vision, firing up Democrats with her attacks on the banking sector. In turn, Warren, the architect of the Consumer Financial Protection Bureau, has been attacked as an uncompromising ideologue.

Obama channeled Warren's words this summer when he made the case for government's role in helping the private sector. The Romney campaign made Obama's speech and his declaration, "You didn't built that," into a mantra of its convention in Tampa, Florida, last week.

Warren said that Romney would undo what she said were the signature accomplishments of Obama's first term.

"Mitt Romney wants to give billions in breaks to big corporations - but he and Paul Ryan would pulverize financial reform, voucher-ize Medicare, and vaporize Obamacare," Warren said.

A political novice, Warren was welcomed by an excited crowd chanting her name and received several standing ovations.

Warren's speech gave the Harvard Law School professor a chance to join her own fate with that of a national campaign as Massachusetts Democrats encourage her to make her race about the consequences of a Republican-controlled Senate and less about Brown, who remains popular in the state.

"She's got to make sure people understand what the difference is," said former Massachusetts Governor Michael Dukakis.

FUNDRAISING CONTINUES IN COSTLY RACE

The convention didn't just afford Warren the benefit of a national television audience. Competing in the year's most expensive Senate race, Warren also took time for a little buck raking. Around 200 people attended a fundraiser for Warren Wednesday morning, raising a maximum of $15,000 a plate, across the street from the convention hall.

The audience heard Warren recount a meeting with Kennedy, which brought her on the verge of tears, said former party chair Philip Johnston.

The race has already become the most expensive in Massachusetts history. Through June 2012, the two candidates had spent a combined $46.7 million.

While proving a prodigious fundraiser, and a lodestar for progressives nationwide, Warren struggled this summer against charges that she falsely claimed Native American heritage in employment applications.

Brown launched a website this week attacking Warren for what the campaign calls a record of misleading people about her biography.

Warren has said she was told by her mother that she is part Cherokee, but her campaign's flatfooted response to Brown's attacks left political observers scratching their heads.

Neck and neck in polling throughout the summer, a recent survey of likely voters by Democratic Public Policy Polling found Warren trailing Brown by 5 percentage points. The pair will meet in four televised debates this fall, the first on September 20.

(Editing by Edward Tobin and Doina Chiacu)