A relentless barrage of TV attack ads sponsored by super PACs and not-for-profit groups contributed to the more than $10 million in total spending by candidates and outside money groups in the race for U.S. Rep. Jerry Costello's seat.

Bill Enyart, D-Belleville, won the Nov. 6 race to replace his fellow Democrat from Belleville.

This year's record spending is almost seven times the $1.45 million spent in 2010 in the 12th U.S. House District election, Federal Election Commission records show.

One of the most closely watched races in the nation this year, the battle for the 12th Congressional District was amped up by the fact it was for an open seat in a district the major parties viewed as critical for House control.

Enyart raised nearly $1.17 million, including almost $690,000 from individuals.

Jason Plummer, the GOP nominee from Fairview Heights, raised $1.34 million, including about $630,000 from individuals.

Meanwhile, outside Democratic and Republican groups spent just less than $7.5 million on the 12th U.S. House race, principally on TV attack ads against Enyart and Plummer.

The National Republican Congressional Committee and the Democratic Congressional Campaign Committee each spent about $2 million on attack ads on the opposing candidates, FEC records show.

Enyart defeated Plummer by about 9 percentage points.

In 2010, Costello, the longtime incumbent, raised about 96 percent of the $1.45 million in 2009-2010, while his Republican and Green Party opponents raised the rest, the records show.

Also in that two-year cycle, outside groups spent zero dollars on 12th District candidates, the records show.

The district stretches from Alton to Cairo, in the state's southern tip.

In the 13th U.S. House district, which covers parts of Madison County, including Edwardsville and Collinsville, as well as 14 other counties, candidates and outside money groups spent about $9.3 million.

Republican nominee Rodney Davis, the eventual winner, who hails from Taylorville, raised more than $1.33 million, including $717,509 in individual donations, FEC records show.

Dr. David Gill, the Democratic nominee from Bloomington, raised almost $1.052 million, including $855,816 in individual donations.

John Hartman, the independent candidate from Edwardsville, raised $8,190, with $7,853 coming from his own pocket, FEC records show.

Outside money groups spent about $6.9 million, principally on TV attack ads, during the 13th House race, FEC figures show.

Outside money groups will likely spend even more money on local congressional races, said Kent Redfield, a political scientist at the University of Illinois-Springfield.

"Overall, we're going to spend more money," Redfield said. "Whether Illinois is a battleground again really depends on what's happening on the national level."

Las Vegas casino billionaire Sheldon Adelson, who spent more than $100 million trying to defeat Democratic candidates -- including nearly $600,000 on attack ads against Enyart -- told the Wall Street Journal a few days ago that he plans "to double down" on his political donations in 2014 and beyond.

Jason Bresler, Enyart's campaign manager, acknowledged that Republican-leaning outside money groups could pose a serious threat to Enyart in 2014.

But Enyart will have a strong record to run on by then, Bresler said.

"I think in two years, Bill will have an incredible record to run on based on his constituent services and just who he is," Bresler said. "That's the reason he was elected this time, because of his record."

A key factor in whether Enyart wins re-election will hinge on Democratic turnout two years from now, said David Yepsen, director of the Paul Simon Public Policy Institute at Southern Illinois University Carbondale.

"If that Democratic turnout falls off in 2014 the way it did in 2010 after 2008, then Enyart could be in trouble," Yepsen said.

Under the U.S. Supreme Court's 2010 Citizens United decision, outside political organizations may donate unlimited amounts of money to support or attack federal office seekers as long as those groups do not coordinate their spending with the candidates' campaigns.

Because of Citizens United, the 2012 election cycle was by far the most expensive in modern U.S. history.

President Barack Obama, the Democratic nominee, and Mitt Romney, the GOP nominee, each raised more than $1 billion apiece for their respective campaigns.

Candidates for the U.S. House and Senate collectively raised $1.65 billion for the 2011-12 election cycle, according to the Center for Responsive Politics, a watchdog group.

U.S. House candidates raised about $1.01 billion of that total, while U.S. Senate candidates raised nearly $650 million, according to the center.

The most expensive House race occurred in the Minnesota 6th U.S. House District, in the Minneapolis suburbs. It pitted Michele Bachmann, the GOP nominee, versus Democrat Jim Graves.

Bachmann, a Tea Party leader, raised and spent more than $25.1 million -- or about 10 times what Graves raised and spent. Bachmann, the incumbent, won re-election by 1 percent of the vote.

The influx of so much outside money on a local congressional race can have big drawbacks, including the fact that outside money primarily buys negative ads against their desired candidates' opponents.

This results in greater bitterness and polarization among district voters, Redfield said.

"And it makes it harder for whoever wins to govern because you've polarized the district and made it nasty and contentious," Redfield said.

Costello is retiring in early January after 24 years in the U.S. House, where he served as an influential member of the powerful Transportation Committee.

Enyart, an attorney and former commander of the Illinois National Guard, is set to be sworn in on Jan. 3.

Tim Butler, a spokesman for Davis, the winner of the 13th House District race, wrote in an email that Davis' "impressive fundraising underscores the broad support he has from citizens of the 13th District."

The overall spending from outside groups, Butler wrote in an email, "highlights what Rodney has often said: He looks forward to serving in Congress and working on our campaign finance system to bring greater transparency and timely reporting to these groups."

Davis is set to replace U.S. Rep. Tim Johnson, R-Champaign, who is retiring after 11 years in office.

Before 2012, Johnson had represented the 15th House District. In 2009-2010, during his final campaign, Johnson spent $270,407 on his re-election campaign, while Gill, the Democratic challenger, spent $142,417.

The $9.3 million spent this year in the 13th House race is nearly 23 times the $412,824 Gill and Johnson spent altogether in 2009-2010, FEC records show.

Because of the vast sums of outside dollars that poured into Illinois congressional elections this year, Yepsen said, "The real winners in that race for congress were the TV stations in the 12th Congressional District markets."