Congressional Republicans pushed ahead on Monday on a U.S. tax code overhaul as a Senate panel considered the issue, but risks lay ahead with major intraparty disputes unsettled and President Donald Trump returning soon from Asia as the debate heats up.

While overseas at a leaders conference, Trump tweeted some tax bill suggestions early on Monday that were starkly different from the two Republican plans being considered in the U.S. Senate and House of Representatives.

He called on lawmakers to add a highly risky provision to their tax effort: repealing the individual mandate included in the 2010 Obamacare health insurance law that requires Americans to have health coverage or pay a tax to Washington.

Neither of the two Republican plans includes such a politically divisive measure. Efforts by Republicans to dismantle Obamacare, formally known as the Affordable Care Act, collapsed dramatically months ago.

Trump has pushed hard for adding the mandate repeal to the tax-cut package. He tweeted the same suggestion on Nov. 3 just before he departed for his multi-nation Asian tour.

In his latest tweet, he also urged slashing the top tax rate for high earners to 35 percent from 39.6 percent, despite criticism from Democrats that the Republican tax bills are deficit-expanding giveaways to the rich and corporations.

The House retains the existing top tax rate in its bill, while the Senate proposes cutting it slightly to 38.5 percent.

Trump is set to return to Washington on Tuesday. A White House aide confirmed that the president would speak to House Republicans on Thursday ahead of their expected tax bill vote.

"I am proud of the Rep. House & Senate for working so hard on cutting taxes {& reform.} We're getting close!" Trump wrote in his Monday Twitter post.

"Now, how about ending the unfair & highly unpopular Indiv Mandate in OCare & reducing taxes even further? Cut top rate to 35% w/all of the rest going to middle-income cuts?" he added.