Unions and other Democratic interest groups are rapidly closing the gap with their conservative opponents in spending on the midterm elections, using fresh support from well-heeled donors to quicken the pace of expenditures in the final days of the campaign.

Democratic leaders from President Obama on down have assailed spending by outside conservative groups, complaining that the business lobby and other GOP allies are pouring millions of dollars into the election as they shield donors from public scrutiny.

But now independent groups that support Democrats - including unions, environmental organizations and new players - are fast gaining ground, often with some of the same techniques condemned by Democrats. The strategies include using money from nonprofits that can keep their donors secret and tapping into union dues to pay for unlimited attack ads.

Nearly $4 of every $10 spent by independent groups last week was aimed at helping Democratic candidates, according to a Washington Post analysis of campaign finance disclosure filings. The number is a dramatic increase from a few weeks earlier, when Democratic allies were being outspent seven to one, the data show.

Once spending by the parties themselves is added to the mix, Democratic candidates are getting the benefit of nearly half - 46 percent - of independent spending reported to the Federal Election Commission. Many Democratic incumbents are also sitting on flush bank accounts that they have been building since the end of the 2008 election.

The trends mean that, overall, Democrats and their allies still have a good chance of outspending Republicans. The pattern undercuts Democratic attempts to blame well-funded conservative groups for an expected wave of losses when voters go to the polls Tuesday.

"The outrage over spending by GOP-leaning outside groups is a political ploy, selective in its focus and hypocritical in its messaging," said Jonathan Collegio, spokesman for American Crossroads, which has reported spending $30 million on behalf of Republicans so far.

A new 'super PAC'



One of the larger spenders on the left barely existed a few weeks ago. America's Families First Action Fund, a "super PAC" that can raise and spend unlimited money, has dumped more than $5 million into 19 House races over the past two weeks, with plans to spend more than $10 million by Tuesday.

Major donors to the group include Obama campaign bundler Orin Kramer, Taco Bell heir Rob McKay and California real estate magnate George M. Marcus, records show. The super PAC's funding also includes $1 million from a nonprofit affiliate, America's Families First, which does not have to report its donors publicly.

Ramona Oliver, a spokeswoman for the super PAC, said the group has nearly doubled its target list of House seats because of a "mini-surge" in donor interest in recent weeks. The group is focused on races, including three open seats, not targeted by other Democratic allies.

"The general philosophy is to look at districts where we could do our piece to shore up the firewall," Oliver said. "We always know we're David to the right-wing Goliath, but we're trying to balance the scales."

Last week, interest groups spent more than $100,000 in 66 House districts across the country. In 29 of them, the Democratic candidate got more help than the Republican.