A number of disappointed Republicans have torched their voter cards and declared support for the #nevertrump campaign after the billionaire businessman clinched the party nomination following Ted Cruz's resignation.

Such is the resentment towards Trump, many are now readying themselves to vote for the Democrats despite being lifelong Republican supporters.

Photographs of them burning their voter registration cards have appeared on social media, while others say they are prepared to vote for Hillary Clinton.

Donald Trump is not virtually assured of receiving the GOP nomination for the White House but faces a tough task to unite a skeptical Republican Party of his suitability for the role

Dozens of Republican voters, such as those above, have vowed to vote Democrat in a bid to block Trump

Dennis Jordan wrote: 'I've been a lifelong loyal @GOP, since the day I could vote. Tonight, I have unregistered and now am an Independent.'

Lachlan Markay posted a photograph on Twitter of his District of Columbia voter registration card burning.

Ben Howe said: 'If you are #nevertrump then I suggest you accept the implications of what that means. Don't kid yourself. I'm not.'

Growing concern is emerging from once firmly established Republicans after Ted Cruz officially announced he was bowing out of the race for the GOP nomination.

After defeat to Trump in Indiana, he dropped out 'with a heavy heart' as he no longer saw a 'viable path to victory'.

'Tonight, I’m sorry to say … it appears that path has been foreclosed,’ Cruz continued, to shouts of ‘No!’ from his supporters.'

'And so with heavy heart, but with boundless optimism for the long-term future of our nation, we are suspending our campaign,' he added.

Trump appeared in Trump Tower in Manhattan not long after Cruz's and spoke magnanimously about his vanquished rival – who just hours before he repeatedly referred to by the moniker 'Lyin' Ted.'

The billionaire, virtually assured of being the GOP's standard-bearer for the general election in November, called the Texas senator 'a tough, smart competitor' during a 20-minute victory speech.

To formally secure the nomination, Trump needs to win about 200 more delegates with only John Kasich technically still in the race.

However, he now faces an uphill battle to retain unity within the party, given the level of discontent towards him among both everyday voters and party leaders.