Former US presidents George H W Bush and George W Bush will not endorse Donald Trump's candidacy for president, aides have told local media.

This marks a first for the 91-year-old former president Bush, who had endorsed Republicans in the past five elections.

Republican politicians are struggling to define their support, or lack thereof, for Donald Trump.

Mr Trump's remaining opponents dropped out earlier this week leaving him as the presumptive Republican nominee.

Both Bush men had previously campaigned this year for former Florida Governor Jeb Bush, who exited the race in February.

They had each supported past Republican presidential nominees John McCain in 2008 and Mitt Romney in 2012.

Although neither former president has openly attacked Mr Trump or his policy proposals, George W Bush made a veiled criticism at a campaign event for his younger brother saying, "The strongest person usually isn't the loudest one in the room".

"I understand that Americans are angry and frustrated. But we do not need someone in the Oval Office who mirrors and inflames our anger and frustration," George W Bush told the South Carolina audience.

http://www.bbc.com/news/election-us-2016-36214738