Some superstar check writers like Sheldon Adelson, the casino magnate, have no problem with Mr. Trump’s erratic policy proposals, bluster, and past vows to self-fund. Mr. Adelson is talking of a $100 million effort to boost Mr. Trump’s performance in the finale against Hillary Clinton. Mr. Trump, having flip-flopped on a primary promise to shun wealthy donors, now seems only too happy to accept a pledge by Mr. Adelson and others to raise as much as $1 billion for his campaign.

For now, Hillary Clinton, the Democratic front-runner, leads the fund-raising pack with a money machine that has sucked in more than $80 million in super PAC support. Democrats are not shying away from the big-check power of super PACs, creating a new $50 million operation started by major labor unions and the billionaire environmentalist Tom Steyer. At the same time, Mrs. Clinton is campaigning on proposals to rein in the runaway money race. She says it undermines American politics.

What voters think of all this as the price of a particularly raucous display of democracy remains to be seen. But the power of money in politics has grown so much since the 2010 Citizens United decision that its presence is felt ever deeper down the ballot. Ominously, there has been a flood of special-interest money into state judicial races that raises questions about whether judges’ decisions might be affected, according to a report by Justice at Stake, the Brennan Center for Justice and the National Institute on Money in State Politics. The toughest race in Kansas this year is being waged by furious conservative Republicans aiming to oust four members of the state Supreme Court because of their decisions striking down the G.O.P. Legislature’s shortchanging of the state constitution’s school-aid requirements.

Shrewd big-money campaigns financed by the Koch brothers and others have upended the Democrats’ one-time dominance of state legislatures. There are now Republican majorities in 70 percent of two-party statehouses. That success, in turn, has created a farm system for the G.O.P.’s current control of Congress. There, the twin powers of big money and statehouse gerrymandering have made incumbents of both parties unbeatable 90 percent of the time, compounding the gridlock voters complain about. For all the job security, big donors are expected to drive this year’s congressional election spending well beyond the $3.8 billion record set two years ago. Much of this money will surely be wasted, further enriching the new breed of fat-cat campaign operatives, and further alienating voters with toxic advertising. But some of it may tip key races.