Democratic presidential candidate Hillary Rodham Clinton addresses supporters at the Quad-City Federation of Labor's Salute to Labor Chicken Fry at Illiniwek Park, in Hampton, Ill., Monday, Sept, 7, 2015. (Louis Brems/AP)

Democratic presidential front-runner Hillary Rodham Clinton is proposing a federal program to match small political campaign donations as a way to dilute the influence of megadonors and unregulated outside money.

Clinton plans to release details of the plan Tuesday. Her campaign provided a preview Monday, as she campaigned in Iowa. Clinton regularly rails against the Supreme Court’s Citizens United v. Federal Election Commission decision, born of a conservative group’s outside efforts against her in the 2008 presidential race, which allowed corporations and unions to spend unlimited sums on independent political activity.

A pledge to try to overturn that decision and appoint Supreme Court justices who support campaign finance limitations is a regular part of Clinton’s stump speech and often gets applause. Yet she also will rely on outside super PACs supporting her for her 2016 bid and has agreed to cooperate by making appearances at some super-PAC events.

Clinton supports a constitutional amendment to overturn Citizens United, a long-shot bid that would require significant political effort.

Clinton proposes to lower the federal contribution limits for political donations to congressional and presidential candidates who agree to participate in the low-dollar-matching program. That limit is $2,700 for the presidential primaries. Clinton is requesting that amount from supporters now.

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Her campaign did not say where she would cap individual donations or what the new federal match for contributions would be. Both changes would require approval by Congress.

Her campaign said she supports “a reasonable limit on the total amount of public matching funds available to each candidate, but no limit on the number of small donations candidates can receive from their supporters up to the individual donor contribution limit.”

She also would discourage gadfly candidates by setting thresholds for federal matching funds.

“Candidates must first demonstrate that they have sufficient public support for a viable campaign by raising a minimum number of small donations from their constituents,” her campaign said.

Among Clinton’s proposals are some of the key measures that have been pushed without success for the past several years by advocates of stricter campaign finance rules. Implementing them would require Democrats to make major gains in the next congressional elections, or for the issue of big money in politics to emerge as a bipartisan cause.

While there have been flickers of Republican support for legislation to require more robust disclosure of political donations and a small-donor matching program, supporters have been unable to cobble together the kind of backing needed to pass such laws. A constitutional amendment to overturn the Supreme Court decision — an extremely popular idea on the left — is unlikely to gain the required support of state legislatures or the Congress.

The most immediate and tangible impact Clinton could have would be through her proposed executive order requiring federal contractors to disclose their political spending, a move that ad­vocates have urged President Obama to make.