President Donald Trump Alex Wong/Getty Images President Donald Trump on Tuesday expressed disappointment with GOP senators opposed to the latest plan to repeal and replace the Affordable Care Act, known as the Graham-Cassidy bill.

In order to pass Graham-Cassidy, Republicans needed 50 of their 52 members to vote for the bill. Sen. Susan Collins of Maine on Monday became the third GOP senator to come out against it, following Sens. Rand Paul and John McCain.

Trump did not appear pleased with the defections and yet another apparent failure by congressional Republicans to repeal Obamacare.

"We were very disappointed by a couple of senators — Republican senators, I must say," Trump said during a meeting with Republican lawmakers on tax reform. "We were very disappointed that they would take the attitude that they did."

Trump has repeatedly attacked McCain for his vote on Twitter and on an Alabama-based radio show Monday. Trump has also leaned on Paul to get on board with the plan, calling him a "such a negative force" on Twitter.

"And at some point there will be a repeal on my desk, but we'll see whether or not that point is now or will it be shortly thereafter," Trump said Tuesday. "But we are disappointed in certain so-called Republicans."

The ability for Republicans to use the budget reconciliation process, which allows them to bypass Democratic filibuster threats, runs out on September 30. After that date, the GOP must either pass a new budget to use reconciliation again or get Democrats on board with a healthcare bill.