A former Federal Election Commission chairman warned Members on Wednesday that a recent Supreme Court decision could eviscerate the Republican National Committee, the Democratic Congressional Campaign Committee and other party-led organizations.

“The public perception that this is a dramatic change is correct,” Robert Lenhard told the House Administration Committee on Wednesday afternoon. “The consequence is that there will be more corporate spending in elections.”

Lenhard, a Democrat who now works at Covington & Burling, appeared before the panel as part of a Democratic-led legislative response to the recent ruling involving the conservative advocacy group Citizens United. This 5-4 decision lifted many restrictions on televised political ad buys made by corporations, unions and nonprofit organizations in the days before Election Day.

Lenhard said Members on both sides of the aisle are underestimating the “decisive” role that outside organizations will play in close Congressional races, contests in which the candidates now will be helpless in controlling their campaign messages —or worse.

“It will be like an ambush,” Lenhard told the panel.

The former union lawyer also said political committees and candidates undoubtedly will be outspent by corporations and organized labor in the new political landscape. To compete, Lenhard is encouraging Members to scrap the current ban on advertising coordination between party committees and candidates.

“So picture this: An interest group makes a single phone call to raise $250,000 for attack ads in the waning days of a campaign,” Lenhard said in a prepared statement. “The candidate must find more than 100 willing donors, able to give the maximum permissible $2,400 contribution, to answer those ads with an equivalent buy.”

Advancement Project’s Co-Director Judith Browne-Dianis, League of Women Voters President Mary Wilson, Brennan Center for Justice lawyer Ciara Torres-Spelliscy, George Mason University School of Law professor Allison Hayward and Steve Simpson, a lawyer for the libertarian group Institute for Justice, also appeared before the committee.

In a prepared statement, Simpson said Democrats were attempting to scare voters.

“Corporations can no more buy elections with political advertising than they can buy market share with commercial advertising,” Simpson said. “If they could, we would all be driving American cars and drinking New Coke.”

The White House apparently is keeping a close eye on the progress of campaign finance legislation now being crafted by Senate Rules and Administration Chairman Charles Schumer (D-N.Y.) and Democratic Congressional Campaign Committee Chairman Chris Van Hollen (Md.).

President Barack Obama famously criticized the Supreme Court’s conservative majority in his recent State of the Union address. White House ethics czar Norm Eisen also was spotted in the crowds of both Wednesday’s House hearing and a similar Senate panel the day before. On Monday morning, Eisen blogged on the White House’s Web site that the decision could flood the political process with money from foreign-owned businesses and lobbyists.

“The American people have a compelling interest in preventing foreign interests from influencing our domestic political process. A strong legislative response is required given the stakes: Americans’ control over their own electoral process,” Eisen wrote. “That is why the president is working with Congressional leadership to move rapidly to pass legislation that protects our politics from undue special interest influence.”