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U.S. healthcare bill appears doomed after Collins says no

* Senator Collins joins Republican senators saying 'no' to bill

* Protests break out at Capitol Hill hearing (Recasts with Senator Collins saying she opposes bill)

By Susan Cornwell and Richard Cowan

WASHINGTON, Sept 25 (Reuters) - A last ditch Republican effort to repeal Obamacare appeared doomed late on Monday after Senator Susan Collins became the third Republican senator to announce opposition to the bill.

Collins, who joined Senators John McCain and Rand Paul in opposing the legislation, told reporters that sweeping cuts in the Medicaid program was the main reason for opposing the bill to end Obamacare, a top priority for President Donald Trump.

Collins said the bill would have taken more than a trillion dollars out of Medicaid, a program for low income citizens and disabled children, between 2020 and 2036. She also opposed the bill for weakening protections for people with pre-existing conditions, such as asthma, cancer and diabetes.

"So for those reasons, I cannot support the bill," Collins told reporters outside the Senate chambers.

Collins' decision came even after the sponsors of the bill, Lindsey Graham and Bill Cassidy, offered sweeteners for her state, Maine, and Alaska.

For seven years, Republicans have vowed to get rid of Democratic former President Barack Obama's signature healthcare law, which extended health insurance to some 20 million Americans. They believe it is an unwarranted and costly government intrusion into healthcare, while also opposing taxes it imposed on the wealthy.

Collins announced her opposition shortly after the non-partisan Congressional Budget Office said that the number of people with health insurance covering high-cost medical events would be slashed by millions if it were to become law.

Collins said the White House had lobbied her hard in recent days.

“The president called me today, the vice president called me in Maine over the weekend, Secretary Price has called me, it would probably be a shorter list of who hasn’t called me about this bill,” she said.

Television talk show host Jimmy Kimmel, who had become part of the debate on U.S. healthcare legislation in May after discussing his newborn son's heart surgery, had taken aim at the bill in recent days. On Monday he tweeted: "Thank you @SenatorCollins for putting people ahead of party. We are all in your debt."

Senator John Cornyn, the chamber's second most powerful lawmaker, said no decision had been made on whether to have a vote on the healthcare bill. (Reporting by Susan Cornwell and Richard Cowan; Additional reporting by Philip Stewart, Makini Brice Alistair Bell and Timothy Gardner in Washington and Caroline Humer in New York; Editing by Bill Trott and Mary Milliken)