By Caitlin Huey-Burns - April 20, 2012

SOMERVILLE, Mass. -- Having criticized her Republican opponent for voting against a millionaires' tax measure, U.S. Senate candidate Elizabeth Warren said here Friday that she opted not to pay a voluntary higher tax rate in Massachusetts.

"I paid my taxes, and I did not make a charitable contribution to the state," Warren, who worked with the Obama administration to create the new consumer financial protection bureau, said when asked if she paid a 5.85 percent state income tax instead of the standard 5.3 percent -- a choice given to Massachusetts taxpayers.

The likely Democratic challenger to Republican Sen. Scott Brown told reporters at a press conference that "the key issue" is about "the 'Buffett rule' and whether or not millionaires and billionaires ought to pay their fair share in taxes, or should they be permitted to have a free walk and just pay a much lower tax rate than secretaries.” She was referring to the proposed minimum tax rate on those earning at least $1 million per year; earlier this week, the Senate failed to advance a bill creating the new rate. When pressed on the Massachusetts tax, Warren again said, “I paid the taxes that I legally owed. I did not make a charitable contribution to the state.”

The Harvard law professor visited her busy Somerville headquarters Friday to talk about campaign finance reform legislation, and brought with her former Wisconsin Sen. Russ Feingold, who championed the issue during his time in the upper chamber. The two urged the passage of a re-introduced version of the DISCLOSE Act, which would require some outside groups involved in elections to release the names of their donors. Warren and Feingold said Brown made the deciding vote against the original bill’s passage two years ago.

Warren is engaged in one of the most competitive and expensive Senate races in the country, and the man she hopes to replace voted against the "Buffett" bill. Republicans have described the White House push for the new tax rule as a political “gimmick” that does little to reduce the deficit. President Obama visited several key battleground states in recent weeks to promote the legislation as an example of “tax fairness” and equality for the middle class.

On Friday, Warren said the Republicans’ premise that the proposed tax would do little to trim the deficit “is just wrong. . . . There’s plenty of places where that money could be used -- could be used to pay down the national debt; it’s a down payment but a good place to go.”

She asserted that “it’s not a ‘gimmick’ to talk about people paying their fair share. It’s really about whose side you stand on.” Brown’s vote, she said, shows he sides with millionaires instead of middle-class families.

Brown’s campaign called Warren a hypocrite for not checking the optional higher tax rate on her personal income. “The problem with running a campaign based on self-righteousness and moral superiority is that you had better live up to the same standard you would impose on everyone else," said the incumbent's campaign manager, Jim Barnett, in a statement. The Brown team said Warren earned over $700,000 in 2011, adding, “This is the sort of hypocrisy and double-speak voters are sick and tired of hearing from politicians, especially those who can't keep their hands out of others' pocketbooks."

Warren and Brown have recently been jousting over whether to make public their personal tax returns. Warren said Friday she is committed to releasing at least the past two years' returns -- if Brown releases his. “It really depends on what Scott Brown does,” she said.

The two candidates visited Boston’s Fenway Park on Friday morning, each making separate appearances on MSNBC’s "Morning Joe." Warren discussed her campaign’s fight for the middle class and accused Brown of siding with Wall Street, citing Forbes Magazine ranking him as one of Wall Street’s favorite senators. Brown disputed the charge during his turn on the show, saying the Dodd-Frank financial reform bill -- which includes the consumer protection agency Warren helped design -- “never would have passed if it wasn’t for me." Two other Republicans voted for the bill, which passed in the summer of 2010.

Polls show the pair running in a virtual dead heat. Both will hold campaign events in the state over the weekend.