Senate Democrats are planning to hold a vote later this year on a constitutional amendment that would nullify the Supreme Court’s recent decision lifting limits on campaign spending, a key leader said Wednesday.

Sen. Chuck Schumer, a New York Democrat and member of his party’s leadership team in the Senate, made the announcement at the opening of a packed hearing in one of Capitol Hill’s largest committee rooms. An unusual appearance by a retired Supreme Court justice put an obscure committee of the U.S. Senate into the spotlight as members of the panel tackle the question of campaign finance.

Justice John Paul Stevens, who retired in 2010 after more than three decades on the court, told the senators that the unlimited campaign contributions his former colleagues approved in this month’s McCutcheon ruling poses the risk that politicians will pay “more attention to non-voters who give them money” than they do to their own constituents.

After complimenting Stevens for his intellect, Sen. Ted Cruz, a Texas Republican who has been sending signals of his interest in a 2016 presidential candidacy, disagreed. Cruz argued that campaign finance restrictions do nothing but “protect incumbent politicians.” But the Texan also called for ending “the silly game” of allowing super PACs to make independent expenditures so long as they don’t coordinate with candidates.

“A far better system,” Cruz said would be to allow unlimited contribution to candidates “and require immediate disclosure.”

Sen. Angus King, a Maine independent, endorsed Schumer’s call for a vote on a constitutional amendment, introduced by Sen. Tom Udall, D-N.M., citing an “erosion of confidence in our system.”

Sunlight’s view

Mocking the notion — advanced by the Supreme Court in its McCutcheon majority opinion and in Citizens United — that transparency would counter the effect of big money campaigns, Norm Ornstein, a congressional scholar with the American Enterprise Institute, noted that “high priced lawyers, some of whom are in this room” are “working feverishly” to ensure that contributions are not disclosed.

Other witnesses at the hearing included former FEC commissioners Trevor Potter and Donald McGahn and current FEC commissioner Ann Ravel.