The Senate remains on track to start Wednesday's procedural votes in hopes of passing the bill next week.
But Gov. Scott Walker said late last week that he supported Johnson's position.
Five Republicans have expressed opposition to the Senate GOP health care plan.
Sen. Susan M. Collins of ME is also on the fence, saying she is anxious that older Americans will have to pay more and that she won't be able to strip out a part of the bill that defunds Planned Parenthood over its abortion practice.
As Trump and Obama joust over the fate of the bill, the current president disputed the notion of his Fox News interviewer that his predecessor is "leading the resistance" to his administration.
He said he feels "a sense of urgency" to push forward because the health care system is in "full meltdown mode".
The Senate is days away from voting on a Republican plan to repeal and replace Obamacare, but leadership has, for the time being, fallen short so far of securing the 50 votes necessary to pass the measure. The Senate bill would provide for expanded tax-free Health Savings Accounts, and it would also eliminate federal funding for Planned Parenthood for one year.
WASHINGTON (Reuters) - Republican Senator Susan Collins of ME said on Sunday she has extreme reservations about the U.S. Senate's healthcare overhaul and does not think it will be able to pass this week.
Unless those holdouts can be swayed, their numbers are more than enough to torpedo the measure developed in private by Senate Majority Leader Mitch McConnell and deliver a bitter defeat for the president.
India beat West Indies by 105 runs
But, Kohli looked good from the off, and he was helped by the fact that he had a smooth-as-silk Rahane at the other end. During the course of the innings, India went past 300 for the 96th time in ODIs, thus creating a new world record.
Then he criticized two prominent Democratic senators. "They're not addressing the root cause", he said, referring to rising health care costs.
On Thursday, the Senate unveiled its bill, but leaders cautioned that it's just a draft and will likely change before the chamber votes on the legislation.
On Friday, a fifth GOP senator, Dean Heller of Nevada, said he does not support the bill.
Gov. John Kasich, R-Ohio, a Republican primary opponent in 2016, also opposes the Senate plan, telling CNN that "the total number of dollars that are going to be dedicated to Medicaid are not enough".
"It would be so great if the Democrats and Republicans could get together, wrap their arms around it and come up with something that everybody's happy with", the president said.
Under Obamacare, about 20 million more people have been enrolled in insurance plans, many of them under the government's Medicaid program for the poor and disabled, which Republicans now want to cut by more than $800 billion over the coming years even though Trump during his campaign for the White House said he would not curtail it.
She said she intends to wait for a Congressional Budget Office analysis before making a decision.
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