WASHINGTON (Reuters) - U.S. President Donald Trump is pushing Republicans to change their tax-cut bill to include a repeal of the Obamacare mandate that requires individuals to buy health insurance or pay a fine, the House of Representative’s top tax lawmaker said on Friday. House tax committee Chairman Kevin Brady said he has asked the Congressional Budget Office (CBO) to assess Trump’s suggestion and indicated some lawmakers were considering it. Other lawmakers have expressed concern. They said adding such a divisive provision would expose the tax bill to the fierce opposition that doomed Republicans’ efforts in July to repeal the 2010 Affordable Care Act, better known as Obamacare. The act was former President Barack Obama’s biggest domestic achievement. It raised taxes on wealthier Americans to fund healthcare benefits for middle- and low-income people, extending coverage to millions of previously uninsured. Democrats have defended it for years from attacks by Republicans, who see it as Washington intruding on Americans’ healthcare. Since Trump took power in January, he has pressed hard to undo much of Obama’s work. So far he has not secured any major legislative accomplishments in Congress, even though Republicans control both the House and the Senate. “The president feels very strongly about including this (the individual mandate repeal) at some step before the final process. He’s told me that twice by phone and once in person,” Brady told an event hosted by the news outlet Politico. “No decisions have been made ... Importing healthcare into a tax reform debate has consequences,” Brady said. Trump broached his idea in a tweet earlier this week, saying it would be “great” to repeal the mandate “and use those savings for further tax cuts.” Some Republican senators, such as Tom Cotton and Rand Paul, also favor this idea. Representative Tom Cole, a senior House Republican, said Friday that adding on a mandate repeal could cost the tax bill votes. “I don’t want to overload the vehicle,” Cole told reporters, adding that including the mandate repeal would probably be a “deal breaker” for Democrats. Brady also said Friday he would offer “substantive improvements” to the tax bill when his committee begins considering the legislation next week. He gave no details. The tax bill released Thursday would cut tax rates for businesses, individuals and families. Republicans hope to pass it through Congress by year’s end. Democrats oppose it as a give-away to the rich and large corporations. 