Calling for a nationwide strategy to take back control of statehouses and governor’s mansions, Democratic presidential candidate Bernie Sanders told supporters Thursday night that defeating Republican Donald Trump “cannot be the only goal.”

Speaking via online video feed, the U.S. senator from Vermont notably declined to endorse his Democratic rival, presumptive party nominee Hillary Clinton, in the race for the presidency or to officially end his campaign. Instead, he appeared eager to attend the Democratic National Convention in Philadelphia next month, with his supporters in a bid to ensure their voices are heard when Clinton, as universally expected, accepts the party’s nomination.

“We have strong disagreements on some very, very important issues. It is also true that we have some issues in common,” Sanders said, referring to Clinton. “I look forward to working with Secretary Clinton to transform the party [into] a party that has the guts  to take on Wall Street, the pharmaceutical industry, the fossil fuel industry and the other powerful interests that dominate our political and economic life.”

After outlining the key points of his progressive platform, including a single-payer healthcare system, reform of criminal justice and immigration and tackling wasteful military spending, Sanders said the Democratic Party must focus on taking back control from the Republicans at the state and local level.

“This campaign has never been about a single candidate. It is about changing America. It is about changing a campaign finance system that allows billionaires to buy elections,” he said. “Our vision for the future of this country is not some kind of fringe idea. It is not a radical idea. It is mainstream. It is what millions of Americans believe in.”

Sanders has resisted calls from Democratic leaders to drop out of the race and line up behind Clinton now that the campaign is pivoting to the general election.

Sanders met with Clinton on Tuesday evening following her victory in the last primary, in Washington, D.C., but declined to endorse her. A Sanders spokesman said the meeting was “a positive discussion about how best to bring more people into the political process and about the dangerous threat that Donald Trump poses to our nation. 

Sanders’ supporters are planning rallies outside the Democratic National Convention in Philadelphia, July 25-28.