Amid Barrage of Attack Ads, Incumbents Consider Tighter Rules Julie Jacobson/Associated Press Representative Joe Heck, left, and his Democratic challenger, John Oceguera, right, before a debate this month in Las Vegas. WASHINGTON - An onslaught of negative political advertisements in Congressional races has left many incumbents, including some Republicans long opposed to restrictions on campaign spending, concluding that legislative measures may be in order to curtail the power of the outside groups behind most of the attacks. While Democrats have long denounced a 2010 Supreme Court decision that opened the gates on unlimited spending on advertisements, some Republicans are now growing more disenchanted with the system that has allowed the barrage of ads, often by shadowy groups, and the effects it has had on what they see as a sullen and disenchanted electorate. "Once we get back, those that do get re-elected will all be commiserating about all the negative ads," said Representative Joe Heck of Nevada, a Republican who faced ads accusing him of voting against a rape crisis center and against money to help victims of domestic violence, among other things. And that will start the groundswell for reform. Representative Dan Lungren, a California Republican and the chairman the House Administration Committee, which has jurisdiction over campaign finance issues, has been a target of negative advertisements. He has drafted legislation that he said would force more responsibility for the tone and messages of the campaign onto the candidates and the political parties and away from the third-party groups. The staff of Senator Lisa Murkowski, Republican of Alaska, is also working on proposals. The 2010 Supreme Court ruling, Citizens United v. Federal Election Commission, was expected to be an unalloyed advantage to Republicans, who have a deeper bench of rich individuals and corporations willing to finance candidates. The decision has appeared to benefit Republicans over all this election cycle, as Republican money has poured into the presidential contest. Democrats say their third-party allies have also been outspent, by about two to one, in Senate campaigns. But the impact of Citizens United has come with complications, with some Republican incumbents in the House at a disadvantage. Earlier this month, before Republicans surged ahead with an additional $25 million, the total spending and reservations for ad time in the House campaigns has been dead even at $89 million, according to the National Republican Congressional Committee. Conservative donors were confident that the House Republican majority was secure and sent their money elsewhere. Democratic donors, including unions and environmental groups like the League of Conservation Voters, have been more strategic, concentrating their fire on a handful of vulnerable House Republicans. Mr. Lungren said the attacks on him began just months after the 2010 election, with radio advertisements and automated phone calls. They have accelerated into an onslaught of television commercials in what has become the most expensive House race in the country. Mr. Lungren's Democratic opponent is Ami Bera, a doctor. "What I'm trying to do is transform the system so people participating as candidates can be held responsible for what is said," Mr. Lungren said of the legislation he is drafting. He said the 2012 experience could be transformative for other Republicans who have spent the last six months enduring the grim piano music and disconsolate faces of "voters" in negative ad after ad, sometimes against them and sometimes on their behalf but always without their signoff. "We had to see how this worked out for a cycle," he said. Senator John Cornyn, a Texas Republican who runs the group charged with electing Republicans to the Senate, has said he thinks it would be worthwhile to examine the campaign finance system after the election. "Revisiting the federal fund-raising restrictions and coordinated limits on both parties, and even smaller, common-sense steps like requiring electronic filing for federal candidates are a few good things that could be looked at next year," he said in an e-mail. Ms. Murkowski has spoken on the Senate floor in a similar vein. The proposals her staff is drafting have a similar thrust. The odds of legislation passing remain unclear. Senator Mitch McConnell of Kentucky, the Republican leader, has vehemently opposed efforts to require the unveiling of secret donors. "The courts have said that Congress doesn't have the authority to muzzle political speech," Mr. McConnell said in June to the American Enterprise Institute during a speech on campaign finance restrictions. Since the Supreme Court ruling, Democrats in Congress have tried to legislate curbs on campaign advertising. Representative Chris Van Hollen of Maryland and Senator Charles E. Schumer of New York drafted the Disclose Act, Democracy Is Strengthened by Casting Light on Spending in Elections, which narrowly passed the House in 2010 and received majority support in the Senate but fell one vote short of the 60 votes needed to break a Republican filibuster. In the last two years, however, support has waned considerably. When Senate Democrats tried again in May, the measure got just 51 votes.