President Donald Trump and the Republican leadership in the House of Representatives are struggling to gather enough support from Republicans for a bill to repeal Obamacare – which could mean a further embarrassing delay for one of Donald Trump's flagship policies.

Despite optimism from the White House, House Speaker Paul Ryan did not say during a press conference if a vote would be scheduled for later this week, but noted that leadership is making “very good progress” with members.

While leaving that conference, reporters asked House Majority Whip Steve Scalise about the current vote count. “It’s better,” he responded, adding that members have asked questions that leadership is trying to answer.

Meanwhile, during an event honouring members of the US Air Force football team, President Donald Trump kept the pressure up, saying: “I think it’s time now” for Congress to act on the healthcare bill.

“How's health care coming, folks?” Mr Trump said while addressing members of Congress at the White House. “How’s it going? All right, we’re moving along? All right, I think it's time now, right?”

White House economic advisor Gary Cohn told CBS News on Monday that the administration was convinced that they have enough votes in the House to pass the bill. White House Chief of Staff Reince Priebus told the same network, “I think it will happen this week.”

While the bill some retain parts of Obamacare, the American Health Care Act (ACHA) gets rid of the insurance mandate and changes the size and recipients of subsidies.

A former version of the legislation failed to gather enough potential votes in the House, partially as a result of strong opposition from the House Freedom Caucus Republican group – a group of roughly three dozen conservative hardliners who demanded that the new law repeal more of Obamacare’s insurance mandates.

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One of the key sticking points appears to be the MacArthur Amendment, which would allow states to drop Obamacare’s guarantee that preexisting conditions will be covered. Following the introduction of the amendment, the Freedom Caucus said that they would endorse the revision of the bill, but the provision appears to be alienating more moderate Republicans.

Republican representative Frank Upton, former chairman of the House Energy and Commerce committee, the group in charge of healthcare policy, said the Freedom Caucus insisted on the amendment.

“I’ve supported the practice of not allowing preexisting illnesses to be discriminated against from the very get-go,” Mr Upton said. “This amendment torpedoes that, and I told the leadership that I cannot support this bill with this provision in it.”