Washington (CNN) Opinion surveys in recent weeks have shown the brunt of public opinion is opposed to the GOP on health care in terms of both substance and process.

These polls, all taken ahead of Thursday morning's public reveal of the Senate Republicans' health care bill, show the uphill climb Republicans in Congress and President Donald Trump have to sell their plan to repeal and replace much of Obamacare.

Breaking down those who felt most strongly showed an even steeper opposition for Republicans' legislation. Forty percent said they strongly disapproved of the bill, while only 14% said they strongly approved.

A poll from Quinnipiac University earlier in June found 62% of registered voters disapproved of the Republican Party's plan to replace Obamacare, 17% approved and 21% said they were unsure. The June poll was the highest level of disapproval recorded by Quinnpiac University so far, which has polled on that question since March.

Polling has shown a desire for reform to the Affordable Care Act, also known as Obamacare, over an outright repeal.

The CBS News poll showed 57% wanted some changes to Obamacare, 28% wanted a full repeal and replace and only 12% wanted the law to stand untouched.

The Kaiser Family Foundation's tracking poll on Obamacare has found the public to be deeply divided over the law for years, although the poll found a rise in approval for Obamacare in recent months. Kaiser's May 2017 release pegged Obamacare's favorability at 49% to 42% unfavorable.

Republican efforts so far

Polls have found public opinion mixed on Trump's approach to health care and congressional Republicans' maneuvering in recent weeks.

Gallup poll in early June found Trump ranked lowest on health care among a slate of issues from terrorism, his strongest area, to immigration and taxes. Twenty-eight percent said they approved of Trump's handling of health care, while 67% said they disapproved.

Likewise, Trump's overall approval rating is the lowest of any president at this point in his tenure since modern polling. The CBS News poll had Trump's approval at 36%, and a Pew Research Center poll from June 8-18 reported a 39% approval.

The CBS News poll also found opposition to the behind-the-scenes process Senate Republicans used to craft their bill. They wrote the bill without hearings or public debate before making it public Thursday morning. Senate Majority Leader Mitch McConnell has signaled his intention to move on a vote swiftly.

The poll taken before the bill release found 73% of respondents would have preferred a public process to write the bill.