WASHINGTON - A new US Congress convenes Tuesday, with Republicans emboldened by Donald Trump's incoming presidency and pushing their ambitious conservative agenda including cutting taxes, slashing regulations and repealing Barack Obama's health care law.

With the Senate and the House of Representatives remaining in full Republican control, the party's leadership has less than three weeks before Trump takes office, when Republicans will run both chambers of Congress and the White House for the first time since 2007.

Tuesday will see Vice President Joe Biden swear in seven new members of the 100-seat US Senate.

Some 52 new House members will also take the oath, and the chamber was expected to re-elect Paul Ryan as speaker of the House, a role that will have him oversee and guide many of the efforts to impose Republican changes to existing law.

The shift in presidential power will lift what has been a large White House road block against Republican action in Congress.

US House Republicans scrapped Tuesday a controversial rules change that would have gutted a congressional ethics office, after President-elect Donald Trump rebuked the strategy hours before lawmakers were to vote on the measure. "The amendment was removed from the rules package by unanimous consent of the conference," a Republican leadership aide told AFP.

Party lawmakers earlier took bold action just before the new Republican-controlled Congress was seated, acting late Monday night - and without participation by Democrats - to hobble an independent ethics office which has investigated corruption allegations against members of Congress.

"With all that Congress has to work on, do they really have to make the weakening of the Independent Ethics Watchdog, as unfair as it may be, their number one act and priority," Trump tweeted Tuesday.

"Focus on tax reform, healthcare and so many other things of far greater importance!"

House Majority Leader Kevin McCarthy told MSNBC that a primary early goal of the new Congress will be the dismantling of the Affordable Care Act, Obama's signature if controversial domestic achievement that has helped 20 million people gain health insurance.

The issue is stirring heated debate in Washington. Obama will visit Capitol Hill Wednesday to huddle with Democrats about how to defend his health care law from repeal, while Vice president-elect Mike Pence is scheduled to meet on the same day to discuss Obamacare with Republican lawmakers.

Another early task awaits: Senate confirmation of some 20 cabinet-level appointments nominated by Trump as he fleshes out his administration. Senate hearings are expected to begin in the coming weeks.

Some nominees are expected to sail through, notably respected retired general James Mattis, who was picked by Trump to head the Pentagon.

But the minority Democrats have pledged to fight several nominations, including Rex Tillerson, the ExxonMobil chief executive who Trump chose for secretary of state; and Betsy DeVos, a wealthy Republican campaigner for alternatives to public schools, who is Trump's pick for education secretary.

In 2009, the Senate unanimously confirmed seven members of Democrat Obama's administration on the day of his inauguration. This year, in the face of the deeply controversial Trump's rise to power, the opposition is more resistant.

Beyond Obamacare, Republicans have been chomping at the bit for years to do away with several Obama-era regulations, including environmental and corporate restrictions, and to launch a tax overhaul.

Ryan and Senate Majority Leader Mitch McConnell have a catalog of laws ready for passage and implementation.

"We spent all of 2016 getting ready for the possible opportunity of having unified government in 2017," Ryan told CNBC in December.

Trump has expressed support for much of the Republican congressional agenda. But there are disagreements over the massive, $1 trillion infrastructure investment plan that the populist president-elect has promised his constituents.

The coming weeks will also be dominated by the case of alleged Russian cyber attacks against the Democratic Party and a close aide to Hillary Clinton during the election campaign.

Obama slapped sanctions on Russia for trying to influence the outcome of the US election.

But Trump, countering the opinion of US intelligence experts, has expressed doubts that Moscow is responsible. He said Saturday he knew "things that other people don't know" about the alleged Russian attacks.

"It could be somebody else," he said from his private Mar-a-Lago club in Florida, adding that he could reveal details "on Tuesday or Wednesday."