U.S. President Donald Trump seems to be struggling with the way he has decided to approach politics, a former economist at Goldman Sachs told CNBC on Friday.

Jim O'Neill, also a former U.K. Treasury minister, said that the U.S.- China summit on Friday should end with some commitments on Chinese investment and some broad assurances against protectionism, but nothing else much further than that.

"I can't imagine anything grander than that, not least because I'm not quite sure what the hell such an agreement would be really. My mind is frequently baffled by what Trump's advisors are going on about really ... And all of this stuff is sort of stuck in the dark ages, it seems to me," O'Neill, told CNBC at the Ambrosetti Forum in Italy.