Republican National Committee Chairman Michael Steele had a succinct suggestion Sunday for Democrats complaining about third-party spending on Republican candidates this cycle: “Put up or shut up.”

Appearing on NBC’s “Meet the Press,” Steele said he assumed that such organizations were complying with laws, which do not require them to reveal their funding sources. If Democrats don’t like that, they should change the law, he said.

And he also doubted the need to change the law. “I don’t know that it is,” he answered when asked by host David Gregory whether it was “a problem” to have unidentified sources funding political campaigns.

On another show, former White House Deputy Chief of Staff Karl Rove also defended the surge in GOP 527 spending this cycle, saying Republicans are simply trying to keep pace with similar Democratic spending. Rove said on CBS’ “Face the Nation” that he is “for a new system, but right now I am focused on 2010 and trying to level the playing field.”

“I don’t want my party to sit there,” Rove said.

Rove’s 527, American Crossroads, has raised millions of dollars this cycle to aid Republicans.

Democrats have been trying to build a case against what they call “special interest” spending this cycle. On the same show, Democratic Congressional Campaign Committee Chairman Chris Van Hollen said the spending by conservative groups is “pouring in” this cycle, and the public has no idea who is behind the spending. He said he hopes the public will connect the dots to see that special interests are trying to co-opt the political process.

He added that these groups know that Democrats in Congress are trying to force them to reveal their funding sources through the DISCLOSE Act, a bill Van Hollen helped author that has stalled in the Senate.

Special interests, Van Hollen argued, “don’t like the fact that power has been reined in, and they are fighting back.”

Democratic National Committee Chairman Tim Kaine also argued Sunday that such undisclosed donations harmed the political process. “The American people have a right to know who is supporting candidates,” he said during an appearance on ABC’s “This Week.” “That is a bedrock principle.”