Spending on this year's midterm elections is set to reach $4 billion, says a report from the Center for Responsive Politics, helped along by donations from Wall Street, medical and insurance firms, labor unions and outside interest groups. (Watch a discussion about the record spending.) As the CRP notes, that's enough to "run the city of Pittsburgh for two years," or "treat each and every American to a Big Mac and fries." Here's more:

$4 billion

Total projected spending on the 2010 elections, a record for midterms

$2.85 billion

Total spending on the 2006 midterms

$5.3 billion

Amount spent during the 2008 presidential election, the current overall record

$1.64 billion

Projected amount spent on Republican candidates and concerns in 2010

$1.59 billion

Project amount spent on Democratic candidates and concerns

$502 million

Amount raised by House Republicans

$461.5 million

Amount raised by House Democrats

$400 million

Amount raised by Senate Republicans

$347 million

Amount raised by Senate Democrats

$400 million

Amount raised by outside interest groups such as "Super PACs" and labor unions.

$2

Amount conservative groups have spent on advertising for every $1 spent by liberal groups

$87.5 million

Projected amount spent by labor union the American Federation of State, County, and Municipal Employees, primarily on Democratic candidates and concerns. It is the biggest outside spender in the midterms.

$75 million

Projected amount spent by the U.S. Chamber of Commerce, primarily on Republican candidates and concerns

$109 million

Amount donated to political candidates, parties, and interest groups by retirees. These donations "slightly favor" Republicans, says the CRP

$102.8 million

Amount donated to political candidates, parties, and interest groups by lawyers and law firms. These donations favor Democrats by a ratio of 3 to 1

$141.6 million

Amount California GOP gubernatorial candidate Meg Whitman has spent on her own campaign, as of October 22

Less than $5,000

Amount Alvin Greene, Democratic senate candidate for South Carolina, has raised in his race against Republican opponent Senator Jim DeMint

63%

Share of total Wall Street donations going to Democrats in March 2009

67%

Share of total Wall Street donations going to Republicans in September 2010

56%

Share of total energy industry donations going to Democrats in January 2009

74%

Share of total energy industry donations going to Republicans in September 2010

$3.3 billion

Projected spending on political advertising in 2010 — with two-thirds of it going to TV — according to Wells Fargo



$50 million

Amount of that money to be spent on internet advertising

1,773

Number of political ads that will have aired during ABC's "Dancing with the Stars" over the course of the election

Sources: Center for Responsive Politics, Washington Post, Bloomberg, Wall Street Journal, Ad Week, NPR, The New York Times