Facing resistance from their own party, Senate Republican leaders said Tuesday they would postpone a vote on their healthcare bill until after the July 4th recess.Senate Majority Leader Mitch McConnell wants to provide more time to make changes to the bill to try to convince reluctant GOP senators to vote for the measure."We're going to press on,'' McConnell said, adding he remains optimistic. "We're continuing to talk."Since the nonpartisan Congressional Budget Office said the bill would leave 22 million more Americans without insurance after 10 years, several Republicans senators had said they would not even support allowing the bill to be brought to the Senate floor for a vote.Meanwhile, President Trump&nbsp;invited all GOP senators to the White House for a meeting Tuesday afternoon.But Sen. Susan Collins (R-Maine), a moderate who has expressed serious doubts about the bill, questioned whether revisions would make a difference."I have so many fundamental problems with the bill, that have been confirmed by the CBO report, that it's difficult to see how any tinkering is going to satisfy my fundamental and deep concerns about the bill,'' Collins said on CNN.McConnell is struggling to appease two factions in his party. Centrists like Collins want to lessen the impact of proposed cuts to Medicaid, while conservatives want to go further in repealing benefits provided under Obamacare.Senate leaders hope to continue talks this week, with an eye toward moving quickly when Congress returns after the holiday. McConnell plans to wait for the CBO to review any changes and reissue a score.He can only afford to lose two Republicans given the party's 52-seat majority in the Senate."There's more work that needs to be done, it's pretty obvious," said Republican Sen. Jim Risch of Idaho&nbsp;as he was leaving a Senate lunch with Vice President Mike Pence. Pence ignored reporters questions about the decision. "If more work needs to be done, you shouldn't try to light the fire."But the delay in a vote will give Democrats and other opponents of the repeal bill more time to mobilize, particularly as Republicans return to their home districts during the holiday."We know the fight is not over,'' said Senate Minority Leader Charles E. Schumer of New York.