Today, senators will be asked whether to begin debate on legislation to supplant Obamacare, as Trump and the Republicans promised during the electoral campaign. The Republican leadership in the Senate will push for a vote to decide whether debate will commence on a health care bill, although it is still not clear what the proposal to be brought to a vote actually contains.

The critical vote will count on the participation of Arizona senator John McCain, who is returning to the US Senate for the first time since he announced he has a brain cancer. His vote may turn crucial, as he voiced concerns about the Senate bill and said he would try to address them on the floor, as reported in Reuters.

A loss "would force Senate leaders, who have struggled to amass support for their version of an overhaul, to find another strategy or ditch their plans entirely," as reported in The Guardian.

On Monday, President Donald Trump said Monday that, so far, his fellow Republican in the Senate "have not done their job" in fulfilling their promise to repeal and replace ObamaCare, and he urged them to do so this week, as reported in EFE.

"Every Republican running for office promised immediate relief from this disastrous law," Trump said in a public statement, in which he called Obamacare "a nightmare" that lasted for seven years.

The Republicans are divided between their more moderate wing, which favors some aspects of ObamaCare, and their ultraconservative faction, which is reluctant to allow any government intervention in people's lives, including when it comes to mandating that people acquire health care coverage.