But while the President's tweets monopolized media coverage over the weekend, lawmakers have plenty of other work, including important action on health care and defense.
House Republicans are aiming to finalize their Obamacare repeal bill that includes some replacement components. Two key committees are expected to markup the proposal - starting as early as Wednesday. Democrats will propose a slew of amendments in an effort to force Republicans to go on the record on a broad range of issues.
GOP leaders are expected to hold more "listening sessions" in an effort to keep their conference on the same page but continue to face some stiff resistance from a bloc of conservatives.
The House will vote on defense appropriations bill -- the first spending bill as GOP leaders eye an end of April deadline for passing a funding bill to avoid a shutdown.
The Senate returns to session Monday afternoon and will debate rolling back an Obama-era Labor Department rule that Republicans say is onerous because it requires companies bidding for large federal contracts to disclose past labor violations and alleged violations. Republicans call it a "blackmail" rule because they think labor unions could use the threat of public disclosure to win concessions from employers.
Republicans are using the special legislative tool known as the Congressional Review Act to get rid of the regulation. The House has already passed it and Trump is expected to sign it.
Later this week, the full Senate is expected to vote on Seema Verma to head the Centers for Medicare and Medicaid Services. She's expected to be a central administration player in repealing and replacing Obamacare.
On Tuesday, the Judiciary Committee will hold a hearing on Rod Rosenstein to be the deputy attorney general.
This hearing will be of interest because of the controversy surrounding Attorney General Jeff Sessions and his decision to recuse himself from any potential investigations into the Trump campaign and Russia's alleged interference in the election. If he is confirmed as the second in command at DOJ, Rosenstein would become the person with oversight of any of those investigations.
Also Tuesday, National Security Adviser Lt. Gen. H.R. McMaster will testify before a closed session of the Senate Armed Services Committee. Because he is staying on active duty to keep his rank, he will require the approval of the Armed Services Committee and later the full Senate.
Sen. Lindsey Graham in his capacity as chairman of the Foreign Operations subcommittee of Appropriations is holding a seemingly timely hearing Tuesday with ambassadors of several countries that neighbor Russia -- including Georgia, Poland and Ukraine --- to examine Russian intentions in the region.