In each case, the president was probably playing good politics, as none of these proposals would be broadly popular. The BAT would have hit retailers who might have passed the cost onto consumers with higher prices. Millions of Americans in states like New York, New Jersey, Illinois, and California benefit from deducting their high local taxes off their federal bill. And tens of millions more take advantage of 401(k) plans, which allow employees to accrue investment earnings that won’t be taxed for decades to come.

Then again, there’s probably not a single lucrative tax increase that would poll well among the nation’s vast middle class except for those that target only the wealthy or Wall Street. And that’s the essential challenge Republicans are facing as they write their tax bill: Do they want to enact comprehensive tax reform, or do they simply want to cut people’s taxes?

There have been plenty of indications over the last few months that Trump and Republican leaders in Congress would have different answers to that question. For years, Ryan and his allies in the House have talked up the idea of a “once-in-a-generation” reform that would simplify the code, cut rates both for businesses and individuals, and pay for it by eliminating exemptions, deductions, and other loopholes that taxpayers use to their advantage. Implicit in that goal is the need to make difficult political choices; every loophole is someone’s prized and essential tax break, with a team of highly-paid lobbyists fighting to keep it. “We will not wait for a path free of obstacles because it does not exist,” Ryan said in a speech in June. “And we will not cast about for quick fixes and half-measures.”

Trump, however, doesn’t talk nearly as much about tax reform as he does about tax cuts—specifically, the “biggest tax cuts ever in the history of this country.” While he’s embraced the idea that Republicans can simplify the code so that people can file their taxes on a postcard, he rarely talks about the tradeoffs that’ll be required to make it happen—except when he’s ruling them out.

Again, from a purely political perspective, this makes sense. Voters probably care less about reform than if they’re going to pass less money to the government, and by how much. And if there’s a through-line in the president’s advocacy, it’s that he’s trying to keep Republicans focused on helping middle-income earners more than the wealthier constituents that have traditionally benefitted from GOP tax proposals. Trump has reportedly persuaded congressional Republicans to keep the current 39.6 percent tax bracket for millionaires, a move that could blunt Democratic attacks that the plan is skewed in favor of the rich.

But Republicans in Congress need the president to be a salesman not just for the popular parts of the tax plan but for the unpopular parts as well, said William Gale, co-director of the Urban-Brookings Tax Policy Center and a former White House senior economist under President George H.W. Bush. “What the president can do is essentially provide air cover for Congress,” Gale said on Tuesday. “President Trump seems to be doing the opposite of that. Instead of providing air cover, he’s dropping bombs.”