Bernie Sanders speaks in Iowa. (Charlie Neibergall / AP)

Bernie Sanders reminded Democrats at an Iowa fundraiser Saturday night of Hillary Clinton’s shifting stances on gay marriage, the environment and pernicious trade deals.

The Guardian reports:

Echoing Barack Obama’s subtle criticism of Clinton in his speech at the 2007 Jefferson Jackson dinner, the Vermont senator pledged in his prepared remarks: “I promise you tonight as your president I will govern based on principle not poll numbers.” Sanders received a rapturous reception from a raucous crowd, including Sanders supporters who spent his entire speech cheering and applauding the self-described democratic socialist. …

The Vermont senator went on to implicitly call out Clinton, noting she had long lagged behind him on a number of progressive causes. In particular, Sanders cited issues such as gay rights, the Trans Pacific Partnership (TPP) and the Iraq war as “the difficult choices” – a subtle reference to Clinton’s memoir Hard Choices – that he has made. …

Sanders also went after Clinton’s prolonged hesitation on taking a position on the Keystone XL pipeline, a controversial project which would deliver oil from the Canadian tar sands to ports on the Gulf of Mexico. “If you agree with me about the urgent need to address the issue of climate change, then you would know immediately what to do about the Keystone pipeline,” Sanders said. “Honestly, it wasn’t that complicated. …

… Clinton was heavily involved in negotiations [for the TPP] on the deal when secretary of state and described it as “set[ting] the gold standard in free trade agreements in 2012”. However, she came out against it only a few weeks ago under political pressure from the left in the Democratic party.

Sanders pointedly said of the TPP, “It is not now, nor has it ever been, the gold standard of trade agreements. I did not support it yesterday. I do not support it today. And I will not support it tomorrow.”