President Trump is giving outsiders and drain-the-swampers a bad name.

A president who comes to power with little dependence on either party and wins election by running against the special interests, could, in theory, do a lot of good work. He could use his popular support to push reforms that are in the national interest but have gotten stuck in Washington. Three examples come to mind — none of which has, at least so far, inspired the president to action.

The first, and in some ways most obvious, is a carbon tax linked to infrastructure modernization.

This would be a win-win-win for the country. The tax would encourage conservation, which would be good for the environment and for slowing climate change. Republicans would have reason to cheer a market-friendly approach, as opposed to government picking energy winners and losers; GOP luminaries such as James A. Baker III and George P. Shultz have endorsed such a tax.

Some of the proceeds could be used to augment the earned-income tax credit, to counter its regressive nature. That would give Democrats reason to cheer.

The rest of the revenue could be distributed to states to spend on infrastructure. The federalism would make Republicans happy. Blue states could spend more on mass transit, making Democrats happy.

This makes such sense that you might think it would pass even without a push from an above-the-fray president, but it won’t. Republicans are too bound to their no-tax ideology. Democrats might object to the loss of federal control. Special interests, deserving and otherwise, from Amtrak to windmill companies, would clamor for a piece of the pie. Presidential leadership would be needed to keep those interests in check and the deal on track.

Then there is immigration reform. This is another case where the shape of a compromise is well-known, but where neither side can say yes without a strong push.

A deal would offer undocumented immigrants a path to legalization, in theory cheering Democrats, while stepping up enforcement to block further illegal immigration, in theory cheering Republicans. Congress could then work out how many legal immigrants, and of what sort, the country should accept in the future. Easy, right?

Well, no. Most undocumented people would welcome such a deal to bring them out of the shadows, but their professional advocates, and therefore many Democrats, would object to anything short of citizenship. Republicans who clamor for strict enforcement would, in many cases, object to the most efficient method: holding employers accountable for hiring undocumented workers.

Again, therefore, you would need presidential leadership. Trump, strange as it may sound, would be well-positioned to push such a deal. Though he called for deporting the 11 million undocumented people in the United States, he also said that the “good” ones could quickly return. The makings of a deal are there — and could include some segments of his wall.

For tax reform, too, the outlines of a deal are in theory universally admired: cap or abolish the deductions that taxpayers can claim — the “loopholes” — and then lower the rates that everyone must pay.

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The universal admiration quickly wanes, however, under special-interest assault. Realtors in every congressional district explain why the mortgage-interest deduction can’t be disturbed. Hospitals, churches and universities remind Congress that opposing the charitable deduction is un-American. Folks from financial services recount how the elderly will go hungry without tax-advantaged 401(k) accounts.

Realistically, the best hope would be not to abolish any of these deductions but to cap how much relatively wealthy people could claim in any given year. And to accomplish even such a cap would require the attention of an above-the-swamp president, making a case for the country at large.

You may think the president is on board for this one, because he talks a fair bit about tax reform. But so far, what he seems to have in mind is only tax cuts, which might be popular in the short term but would send the already sky-high national debt into outer space. The only tax benefit that Republicans seem to want to target is, conveniently, the one that blue states depend on: the deduction for state and local taxes.

Which is in keeping with the policy predilections Trump has shown, to the extent he has shown any so far: conventional, down-the-line Republican, from tax cuts for the rich to the far more difficult, and politically fraught, push to repeal, and possibly replace, Obamacare. Meanwhile he leaves on the table the opportunities his unconventional path to the presidency had opened for him.

Is this because he’s just not interested in policy? Or because he has a plutocrat’s natural inclination toward the Republican playbook? I don’t know. I do know he’s missing a chance to show the good that a leader unbeholden to party orthodoxy really could do in this town.

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