Senate Majority Leader Harry Reid (D-Nev.), right, and Senate Minority Leader Mitch McConnell (R-Ky.) testify before the Senate Judiciary Committee about political donations and freedom of speech in the Hart Senate Office Building on June 3. (Chip Somodevilla/Getty Images)

In dueling testimony, Senate Majority Leader Harry M. Reid (D-Nev.) and Minority Leader Mitch McConnell (R-Ky.) offered sharply competing glimpses of the state of political campaigns, one calling for a radical overhaul of the system and the other defending the status quo.

Reid and McConnell, making a rare joint appearance before a legislative committee, jousted over the majority leader’s support for amending the Constitution to allow for the regulation and limitation on political contributions, a long-shot bid by Democrats coming in a campaign year when they are being badly outspent by conservative activists.

Reid said such a law would “bring back sanity” to a system increasingly dominated by billionaires funneling donations to political groups working outside the regulated system of candidates and official party committees, following a pair of recent Supreme Court cases that expanded the ability of corporations, unions and other special interests to directly advocate in political campaigns.

“The decisions by the Supreme Court have left the American people with a status quo in which one side’s billionaires are pitted against the other side’s billionaires,” Reid told the Judiciary Committee.

The hearing came as Democrats have tried to sully the political reputation of the industrialist Koch brothers, who have made large contributions to Americans for Prosperity and other conservative groups. AFP has poured alarming sums into the battle for control of the Senate, particularly Democratic-held seats in North Carolina and Louisiana.

Republicans have countered that Democratic aligned groups, such as Majority PAC, run by top advisers to Reid, have poured millions of dollars into states such as Kentucky, where they are aggressively trying to deny McConnell his reelection. Tom Steyer, a billionaire investor, has pledged to collect $100 million to mount campaigns through Next Generation against Republicans that the liberal group deemed opponents of climate change proposals.

Breaking from his prepared testimony, Reid ventured into a long discussion of his own political history, beginning with his first, unsuccessful bid for the Senate in 1974 and the strict rules that applied then. After winning in 1986, he faced a difficult reelection in 1998 during a time when he could directly solicit unlimited donations from special interests for state party committees, money that was then spent on his narrow win. “I felt so unclean, for lack of a better word,” he said, suggesting that he hoped he wasn’t “corrupted” in the process.

After a strict 2002 law banned federal lawmakers from soliciting those donations, the outside money waned, until the January 2010 “Citizens United” case that opened up more spending for outside groups – just as Reid headed into a brutally tough campaign. “Then comes 2010, back into the sewer,” he said.

Reid won that reelection in large part because of the work done by Patriot Majority, a nonprofit that accepts unlimited donations and does not disclose its donors. That group, which was also run by Reid advisers, waded into the GOP primary by critiquing the frontrunner, helping secure the nomination for a staunch conservative who was an easier opponent for the majority leader, who won by 5 percentage points.

McConnell countered that candidates had to compete in the “political marketplace” and that the First Amendment allowed for the “free exchange of ideas” not restricted by limits set by the government. “It would empower politicians in Congress and in the states to write the rules, to write the rules, on who gets to speak and who doesn’t,” McConnell told the committee of the proposal, drafted by Sens. Tom Udall (D-N.M.) and Michael Bennet (D-Colo.).

The leaders’ statements took on personal tones at times, sometimes recalling their own tough reelection races and other times connecting the rules to today’s campaigns.

McConnell made one point each side agreed with: “Everyone on this committee knows this proposal is never going to pass Congress.”

Because it is an amendment to the Constitution, it would require a two-thirds supermajority in both the Senate and House to then be sent to the states, where it would need three-fourths of the states to ratify it before it became law. In today’s gridlocked Congress, such a high hurdle will not be cleared, but supporters believe that giving the issue some legislative elevation now might set the groundwork for eventual passage in years to come. The Senate Judiciary Committee is likely to hold several follow-up hearings in the coming weeks.

McConnell did not make a direct mention of his own race this year, but he noted that “no politician likes to be criticized,” and that he was among those who get criticized more often than most. “But the recourse to being criticized is not to shut up your fellow citizens,” the GOP leader said.