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Trump hailed a "historic" victory Wednesday as the US Congress passed a massive Republican tax cut plan, handing the president his first major legislative achievement since taking office nearly a year ago. / AFP PHOTO / SAUL LOEB        (Photo credit should read SAUL LOEB/AFP/Getty Images)
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(CNN) —  

A White House official said Thursday that it is “appropriate” for Wisconsin Sen. Ron Johnson to have concerns about the tax reform package being pushed by the White House.

Republicans can lose only three of their 52 members and still pass the bill. Johnson announced he’s opposed to the bill in its current form, making things more difficult for the White House and GOP leaders.

“If they can pass it without me, let them,” Johnson told The Wall Street Journal. “I’m not going to vote for this tax package.”

Speaking from the White House podium during the beginning of the press briefing Friday, Kevin Hassett, chair of the Council of Economic Advisers, said he met with Johnson on Thursday at his office and acknowledged that he has “serious concerns, and it’s appropriate at this point in the legislative process to bring those forward.”

Hassett also said President Donald Trump has supported “regular order” to properly scrutinize the bill and keep it open for public debate. The House passed the tax bill earlier this week, and 13 Republicans opposed the bill.

Trump has publicly lambasted a handful of senators who have voted against him on previous bills.

In late September, Trump tweeted about Arizona Republican Sen. John McCain’s opposition to the GOP’s health care overhaul: “John McCain never had any intention of voting for this Bill, which his Governor loves. He campaigned on Repeal & Replace. Let Arizona down!’