President Trump on Monday urged congressional Republicans to kill Obamacare's "unfair and highly unpopular" individual mandate in tax reform legislation that the House could vote on as early as this week.

"I am proud of the [Republican] House and Senate for working so hard on cutting taxes (and reform)," Trump tweeted Monday morning, a day before he returns from his 13-day trip to Asia.

"Now, how about ending the unfair and highly unpopular individual mandate in [Obamacare] and reducing taxes even further?" he continued. "Cut the top rate to 35 percent [with] all of the rest going to middle income cuts?"

The president's tweet comes days after the Senate Finance Committee released its own tax reform proposal, which sets the top individual tax rate at 38.5 percent and does not include a repeal of the individual mandate.

The White House and several Republicans have argued that repealing the individual mandate would save approximately $338 billion over the next decade, creating enough revenue to offset tax cuts in the current legislation.

Congressional GOP leaders have said their goal is to pass tax reform by Christmas. House Rules Committee members are expected to meet Wednesday to set up debate on the tax bill in the lower chamber, potentially paving the way for a floor vote on Thursday.

"We're getting close!" Trump tweeted Monday.