If Senator McCain wants an opening to make a run at New York’s 31 electoral votes — something we encouraged him to do in an editorial yesterday — he has just been handed the issue to run on. The Assembly Democrats yesterday voted to pass their millionaire’s tax, which, if it becomes law, would send the top marginal rate soaring in New York City and the state and threaten the very sector of our economy that is producing the most tax revenues for a state in the midst of a spending crisis.

It doesn’t look like the local Republicans are going to take the lead in this fight. On the contrary, as our Grace Rauh reports, passage of the millionaire’s tax in the Assembly had enough Republican support that Assemblyman Richard Brodsky was predicting last night that passage of a form of the tax was a virtual certainty in Albany, even in the face of opposition from our Democratic governor. The new majority leader of the Senate in Albany, Dean Skelos, has been pretty good this time around, but once, in 2003, backed a form of the millionaire’s tax.

E.J. McMahon of the Manhattan Institute noted last night that the latest moves would make the state income tax’s top marginal rate of 8.6% the highest in 21 years. “In other words,” he said in an e-mail message, “this is almost a full percentage point higher than where Mario Cuomo left us.” Of course, that doesn’t include the rate for affected taxpayers in New York City, for whom the marginal rate would be something on the order of 12.25%.

Combined with the payroll tax increases and income tax increases Mr. Obama is readying, New York’s high earners could, if Mr. Obama wins, be paying what Mr. McMahon calls “over 50% easily.” Given what’s afoot in Albany, it might not end there. The speaker, Sheldon Silver, is a sucker for millionaire taxes, and the unions and the Working Families Party will be pushing for more. Working Families has a proposal that could boost the marginal rate on those earning more than $10 million by 7 percentage points. That could bring the marginal rate for the highest earners in the city to more than 17%.

This has the makings of fertile ground for Mr. McCain right now and right here. There are signs that Mr. Obama is taking New York State for granted, with an effort here that could be characterized as perfunctory. Meanwhile, Mr. McCain is much closer to Mr. Obama in New York State than Mr. Kerry was, at this point four years ago to President Bush in the state. When President Reagan made his successful run for the presidency, a tax rebellion was under way in California — and he knew how to make the most of it.

So we say to Mr. McCain, come to New York. Here we have a Democratic governor who is starting to move on the spending side, who is opposing a millionaire’s tax being pushed by his own party in the Assembly, and a Republican Party adrift in the midst of a fiscal crisis. Here is a chance to link the national picture to the local picture and point out the damage that tax hikes pose to our most productive sector. It may sound like dreaming for a Republican to hope to win New York this year, but a lot can happen between now and November, and the polls are moving in the right direction. Remember those 31 votes in the Electoral College.