Sen. Bernie Sanders’ (I-Vt.) campaign against former secretary of state Hillary Clinton is becoming increasingly acrimonious, the New York Times reports today.

Though he remains far behind Clinton in the delegate count, Sanders is hoping to inflict a “heavy blow” on Clinton by winning the California primary and is determined to have a vocal presence at the Democratic Convention in July, the Times reported.

The Times said: 

While Mr. Sanders says he does not want Mr. Trump to win in November, his advisers and allies say he is willing to do some harm to Mrs. Clinton in the shorter term if it means he can capture a majority of the 475 pledged delegates at stake in California and arrive at the Philadelphia convention with maximum political power.

Democratic leaders are urging Sanders to stand down to allow Clinton to focus on presumed Republican nominee Donald Trump. But the Sanders camp in recent days has escalated its rhetoric against Clinton and the Democratic National Committee, which it accuses of rigging the debate schedule and taking other measures to give Clinton an unfair advantage. The Sanders camp has also been buoyed by a series of polls showing him faring better against Trump than Clinton.

The Times reports:

Mr. Sanders has sharpened his language of late, saying Tuesday night that the party faced a choice to remain "dependent on big-money campaign contributions and be a party with limited participation and limited energy" or "welcome into the party people who are prepared to fight for real economic and social change." 

Tensions exploded over the weekend at the Nevada Democratic Party convention, where Sanders supporters accused Clinton backers of breaking party rules. His supporters shouted down pro-Clinton speakers and sent threatening messages to the Nevada state party chair.

Democratic leaders called on Sanders to apologize, but the former Burlington mayor instead criticized the DNC’s conduct.

“If the Democratic Party is to be successful in November, it is imperative that all state parties treat our campaign supporters with fairness and the respect that they have earned,” Sanders said in a prepared statement. “Unfortunately, that was not the case at the Nevada convention. At that convention the Democratic leadership used its power to prevent a fair and transparent process from taking place.”

On Tuesday, Sanders beat Clinton in the Oregon primary, but lost narrowly in Kentucky. The Sanders camp has said it is considering asking for a recount in Kentucky.