Rep. Nancy Pelosi was emphatic. Mitt Romney’s refusal to release more than two years of his personal tax returns, she said, makes him unfit to win confirmation as a member of the president’s Cabinet, let alone to hold the high office himself.

Sen. Harry Reid went farther: Romney’s refusal to make public more of his tax records makes him unfit to be a dogcatcher.

They do not, however, think that standard of transparency should apply to them. The two Democratic leaders of the Senate and the House of Representatives are among hundreds of senators and representatives from both parties who refused to release their tax records. Just 17 out of the 535 members of Congress released their most recent tax forms or provided some similar documentation of their tax liabilities in response to requests from McClatchy over the last three months. Another 19 replied that they wouldn’t release the information, and the remainder never responded to the query.

The widespread secrecy in one branch of the government suggests a self-imposed double standard. Yet while American politics has come to expect candidates for the presidency to release their tax returns, the president isn’t alone in having a say over the nation’s tax laws. Congress also stands to gain or lose by the very tax policies it enacts, and tax records – more than any broad financial disclosure rules now in place – offer the chance to see whether the leaders of the government stand to benefit from their own actions.

“Senior public officials, especially members of Congress and presidential candidates, should be required to disclose their tax returns so that the public can monitor potential conflicts of interest,” said Craig Holman, government affairs lobbyist for Public Citizen, a nonpartisan watchdog group.

The question of taxes is particularly pressing this year, as Congress debates whether to extend all or some of the Bush-era tax cuts that are set to expire Dec. 31. At the same time, tax returns reveal assets and investments.

Absent tax information, members of Congress aren’t fully transparent, said Daniel Auble, who heads the personal finance project for the Center for Responsive Politics, which tracks financial disclosures by members of Congress and appointees confirmed by Congress.

“Having a clearer picture of lawmakers’ interests . . . is definitely important in making available to the public what possible influence there could be,” he said. “In terms of transparency, it would be helpful to have more information.”

Among those who did disclose their tax returns: Sen. Claire McCaskill, D-Mo., and Rep. Barney Frank of Massachusetts, the senior Democrat on the House Financial Services Committee and a co-author of the Dodd-Frank law tightening regulations on Wall Street.

To Pelosi and some other top Democrats, the focus is on Romney, the Republican presidential candidate, who’s released his 2010 return and 2011 estimates and plans to release his 2011 return when it’s completed, but refuses to release any more. They say the very refusal to release more suggests that he’s hiding something.

"He could not even become a Cabinet member for that lack of disclosure, and now with that lack of disclosure he wants to be president of the United States,” said Pelosi, the House minority leader, who’s from California.

“We’d like to know what’s in those tax returns that he refuses to show to the American public. Did he pay any taxes?” Reid asked in an impassioned speech to the Senate on July 11. Days later, Reid, who’s from Nevada, suggested that Romney’s refusal to release more than two years of tax returns would make him ineligible to serve even as dogcatcher.

Rep. Debbie Wasserman Schultz of Florida, the chairwoman of the Democratic National Committee, also has harangued Romney for refusing to release more tax returns, calling it a “penchant for secrecy.”

All three refused repeated requests from McClatchy to release their own returns, requests that started before the flap over Romney’s records.

Pelosi aides refused, saying she’s disclosed all that Congress requires.

“The leader has filed a complete financial disclosure report as required by law that includes financial holdings, transactions and other personal information,” Pelosi spokesman Nadeam Elshami said. “There has been no question about where Leader Pelosi and Democrats stand on tax policy: We must extend the middle-class tax cuts and end tax breaks for millionaires and use the revenues to pay down the deficit.”

Challenged at a recent news conference to release hers, Wasserman Schultz said she wouldn’t because she wasn’t running for president. “I file full financial disclosure required under the law,” she said.

What’s required by law is written by Congress itself, a broad financial-disclosure statement that offers no direct information on tax liabilities and no requirement for reporting spousal income other than the source – but not the amount – of any income above $1,000. There’s little way of knowing whether that spousal income is $1,001 or $1 million.

Several members of Congress married into money or have wealthy spouses. Topping that list are Rep. Michael McCaul, R-Texas, whose wife, Linda, is an heiress to the Clear Channel Communications fortune, and Sen. John Kerry, D-Mass., whose wife, Teresa, is the heiress to the Heinz ketchup fortune. Pelosi’s husband, Paul, heads Financial Leasing Services Inc., a San Francisco-based venture capital and real estate firm.

When it comes to the valuation of investments or reporting of income on the annual disclosure forms, what’s required are broad numbers such as between $250,000 and $500,000 or $1 million and $5 million. That makes it hard to determine how much benefit a lawmaker might get from competing tax plans.

“They just don’t provide the same level of detail as a tax return,” said Darrell West, a specialist on governing and a vice president of the Brookings Institution, a center-left research center in Washington.

Most members won’t release that kind of detail.

Only 17 members shared their detailed tax information with McClatchy. Another 19 refused, but the majority of them stressed that they comply with congressional disclosure requirements.

Of the lawmakers who shared their tax returns, most got large deductions for interest on personal and investment real estate. That’s useful information for taxpayers, since a revamp of the tax code is expected in the next few years.

McClatchy isn’t releasing the tax returns under the terms of the agreement with the lawmakers. Reporters requested the returns to examine in detail how members would be personally affected by changes in tax laws being debated in Congress including income tax rates, as well as taxes on capital gains and dividends and deductions for such expenses as home mortgage interest. In exchange for sharing their returns, members were told their actual returns would not be made public.

Most lawmakers, however, chose to keep their tax liabilities a secret.

“First your publishers and editors and execs should publish their tax returns. They have great influence over public policy,” Rep. Gary Ackerman, D-N.Y., said in an emailed response. Ackerman, who was dogged in 2010 by allegations of a sweetheart stock purchase, isn’t seeking re-election, so his term ends in January.

“Are you guys asking the president to turn over his college records? Or asking him to turn anything over of any kind?” responded Allen Klump, the communications director for Rep. Jeff Duncan, R-S.C.

“Thanks, but we will not give you Sen. Rockefeller’s tax return. Good luck on the project,” said Vincent Morris, a spokesman for Sen. Jay Rockefeller, D-W.Va., whose family surname is synonymous with wealth.

Several lawmakers said they’d disclose what’s required and no more.

Rep. Renee Ellmers “files a financial disclosure form each year in accordance with House ethics rules and this is publicly available,” said Tom Doheny, a spokesman for the North Carolina Republican.

Rep. Joe Wilson “has submitted a financial disclosure form, which is required by law and available to constituents as a matter of public record,” said Caroline Delleney, a spokeswoman for the South Carolina Republican.

Constituents generally know where their particular lawmakers stand on the issue of the expiring tax cuts because the two major political parties have well-defined views. But there’s more at stake than just tax brackets, and voters often have little feel for whether their members of Congress would benefit or be harmed by changes that are under consideration.

From the financial disclosure forms, constituents can, with some work, surmise how lawmakers’ investment income might be taxed under competing plans. Given their salaries, lawmakers would fall into the higher tax bracket for dividends, but it’s unclear where they’d fall individually on the income scale.

“There are clearly some people above (the $250,000 threshold). There’s a bunch of people who might or might not be affected, and you can’t tell,” said Roberton Williams, a senior fellow at the Tax Policy Center, which is run by the Brookings Institution and the centrist Urban Institute.

Tax data isn’t always a panacea, however.

Missouri Democrat McCaskill was one of the few senators who provided McClatchy with a tax return. Her 1040 form lists her as married filing separately, showing an adjusted gross income of $193,384.

But her husband, Joe Shepard, is a wealthy businessman whose investments sometimes have put her in an unpleasant spotlight. His investment in a reinsurance company in Bermuda – the same country in which a Romney investment has been criticized by Democrats – brought allegations from Republicans in 2009 of tax dodging. Shepard no longer hold the investment.

McCaskill does report dozens of her husband's investments in her annual financial disclosure statement, with more detail than required. But each still is listed only under ranges of values, not precise amounts.

That’s another reason advocacy groups think that financial-disclosure reporting should be expanded to capture spousal income more fully, and argue that tax data would be a useful, albeit imperfect, tool.

“As public officials, potential conflicts of interest caused by their wealth and assets are a public concern,” said Holman, the Public Citizen lobbyist.

Kaz Komolafe and Farah Mohamed contributed to this article.