WASHINGTON — The Senate’s top Democrat said Tuesday that President Trump’s refusal to release his tax returns is going to make this year’s promised overhaul of the tax code “much harder.”

Sen. Charles Schumer says Trump is opening himself to second-guessing about his motives for supporting different policies and that the average American will think he’s making changes because “it’s good for him.”

Schumer, D-N.Y., said voters are “going to say, ‘Oh, he’s not doing that because it’s good for me, he’s doing it because it’s good for him.’ So for his own good, he ought to make them public. And the big mystery is why he hasn’t.”

Trump, a billionaire real estate magnate, is the first presidential candidate in decades who has refused to release his tax returns. Critics say Trump’s lack of transparency means the public doesn’t have enough information to determine whether his moves as president could represent a conflict of interest.

“I think he just has an obligation to come clean,” Schumer said.