Johnson, one of five senators opposing the bill, said he also would like to review the CBO score.
Senate Democratic leader Chuck Schumer of NY said Democrats have been clear they will cooperate with Republicans if they agree to drop a repeal of the Affordable Care Act and instead work to improve it. And the president called Massachusetts Senator Elizabeth Warren "somebody that's just got a lot of hatred".
Warren, a leading liberal and defender of the Affordable Care Act, has opposed efforts to pass a bill to replace the law.
But Republicans only hold a 52-48 majority in the Senate, with all Democrats expected to vote against the Republican proposal. Ron Johnson of Wisconsin.
"I'm undecided", he said on CBS' "Face the Nation". There's no way we should be voting on this next week.
Johnson says he's made his views clear to the party leadership and the White House. Still, Schumer acknowledged it was too close to call as to whether Republicans could muster enough support on their own to pass the bill.
He told ABC's "This Week" the GOP has "at best, a 50-50 chance".
The release of the Senate Republicans' draft health care measure, coming on the heels of the demise of the filibuster for Supreme Court nominees, provoked a spasm of hard feelings in the chamber and questions about whether senators could restore its now-quaint reputation as the World's Greatest Deliberative Body. The Affordable Care Act bans lifetime limits and requires insurers to cover various so-called "essential health benefits" which states could waive under the Senate plan.
GOP Senator Susan Collins of ME, who has not yet said she will vote against the bill, expressed reservations towards it to news outlets today. Collins, who also opposed proposed cuts to Planned Parenthood, said she was awaiting the CBO analysis before taking a final position on the bill. Activists and health organizations have argued that the bill's sweeping cuts to Medicaid would be life-threatening to many Americans.
Trump said he does not think Republicans voicing objections to the party's proposal are "that far off" from supporting it. Senator Susan Collins (R-M.E.) counts at least seven more, including herself, who are troubled by the bill's cuts to Medicaid.
She says she intends to wait for a Congressional Budget Office analysis before making a decision.
"I have very serious concerns about the bill", Collins said in an interview with ABC's This Week.
U.S. President Donald Trump has again branded Democrats as "obstructionists" for not working with Republicans to reach a deal to replace what's commonly known as ObamaCare. But I think we're going to get it.
The Senate bill is similar to the House bill but includes additional funding to stabilize the Obamacare health insurance exchanges and, so far, does not contain a provision that would penalize people for not having health care coverage.
It aims to deliver on a central campaign promise of President Donald Trump to undo former President Barack Obama's signature health-insurance law, which has provided coverage to 20 million Americans since it was passed in 2010.