As the presidential primaries begin to heat up, the candidates, especially the second- and third-tier challengers to the early favorites, are pressing ever more bold ideas into the debate. Martin O’Malley won the prize last week with the most ambitious Wall Street reform proposal in the campaign so far. And before O’Malley, Bernie Sanders had even revived the idea of a “single payer” health care system for all.

Republicans are doing the same on the right. Rand Paul has proposed “blowing up” the tax code, and replacing it with a single 14.5 percent rate on individuals and businesses. Three other Republicans have also jumped on the flat-tax bandwagon.

This is the stuff presidential campaigns are made for: bold ideas to capture a committed base, and launch candidates into nominations.

But to listen to these ideas requires a certain suspension of disbelief. Because putting aside the problem of divided government, none of these ideas has even a shot in Washington until we address the corrupting influence of money in politics.

Consider O’Malley’s reform of Wall Street. The finance sector gives more to congressional campaigns than any other sector of the American economy. It spends more through super PACs than any other sector as well. And as the last eight years have taught Democrats, it spends its money strategically.

In 2008, 51 percent of finance’s money went to Democrats. In 2010, that fell to 47 percent. The Democrats then enacted Dodd-Frank. Finance responded: In 2012, Democrats received 32 percent of finance’s contributions. In 2014, it received 37 percent. That number is certain to fall if 2016 is a rally against Wall Street. Can the Democrats as a party afford a committed Wall Street reformer for president— at least so long as they depend on Wall Street’s cash to stay competitive?

The same is true for Republicans and tax reform. The tax system is a complicated mess for many reasons. But one reason is the way it helps Congress finance its campaigns.

Think about the R&D tax credit, which has been a “temporary” provision in the tax code since 1981. Each time the credit is about to expire, Congress rallies support to renew the tax break from those who benefit from it. “Support” means campaign contributions. As the libertarian Institute for Policy Innovation puts it, “this cycle has repeated itself for years ... Congress essentially uses this cycle to raise money for re-election, promising the industry more predictability the next time around.”

These are not isolated examples. Practically every single important issue in Washington is now held hostage to big money, from climate change to addressing the debt. And amazingly, candidates from both parties are beginning to acknowledge this. Republicans like Lindsey Graham are openly criticizing Citizens United. And O’Malley and Sanders have both endorsed fundamental changes to the way campaigns are funded—at least, as Sanders said in his announcement, “in the long run.”

“In the long run”? What does Sanders believe he will get done in the short run, while Congress remains dependent on campaign cash from the very entities his reforms would dramatically affect? We live in a constitutional republic. Fundamental policy change requires Congress. But without a Congress that can act, sensibly, talk of revolution is just that.

None of these bold ideas for reform, from either Republicans or Democrats, are credible until they include a plan for liberating Congress from its corrupting dependence. Yet not a single candidate for president has offered a plan for that liberation. Almost every serious candidate acknowledges the problem. Yet none has come close to a plausible way to address it.

If these reformers are to be taken seriously, they need to give us a plan. They need to show us how they will deliver a Congress, as former governor and Republican presidential candidate Buddy Romer put it, “free to lead”—first. They need to identify the steps they will take immediately upon coming to office that would free Congress from special-interest money. They need to convince us those steps are plausible, and give us a reason to believe they can succeed.

Because if they can’t, maybe we shouldn’t be looking for another Superman or Superwoman for president. Maybe we should be looking for a leader who could make the most of a broken democracy. President Obama has done an amazing job over the past five years with a Congress that cannot function. If the reformers want us to believe they would be a president who could do more, they need to tell us how. Before we start another “change you can believe in” campaign, someone needs to give us a plan that would make change believable again.