Bernie Sanders delivered a simple message Tuesday at a press conference outside his campaign's Capitol Hill office: The Democratic Party needs to be transformed, and he plans to push for that all the way through the Democratic National Convention in Philadelphia.

Speaking just a few blocks from Congress with campaign manager Jeff Weaver and national spokeswoman Symone Sanders (no relation) at his side, Sanders ticked off his list of priorities to change the party.

"We need a person at the leadership at the DNC who is vigorously supporting and out working to bring people into the political process," Sanders said, before stressing the need for "the most progressive platform ever passed by the Democratic Party. A platform which makes it crystal clear that the Democratic Party is on the side of working people."

The Vermont senator called for replacing Democratic National Committee chairwoman Debbie Wasserman Schultz, enabling open primaries so non-registered Democrats can vote, and better staffing to prevent long lines and difficulty being able to vote. Sanders pointed to Arizona, where both Democratic and Republican officials denounced the long lines and fewer polling stations available in the March 22 primary. Former Secretary of State Hillary Clinton won that contest.

"How many people simply gave up their right to vote — gave up their right to vote and walked away," Sanders said. "We are taking for granted that in California it will take weeks for votes to be counted and I'm not sure the votes have yet been counted in Puerto Rico."

"We also need obviously to get rid of superdelegates," Sanders said. "The idea that we had 400 superdelegates pledged to a candidate some eight months or more before the first ballot was cast is to my mind absurd. And we need to also make sure that superdelegates do not live in a world of their own but reflect, reflect, the views of the people of their own state."

The press conference came hours before Sanders is set to sit down in a private meeting with Clinton, who has clinched the required number of delegates needed for the Democratic nomination.

The Vermont senator struck many of the same notes in a private lunch with Senate Democrats just before his news conference, where Sanders did not give any indication of what his political plans would be after the results roll in from the D.C. primary Tuesday night, senators said.

Instead, Sanders discussed lessons from the campaign trail and stressed to his colleagues that the Democratic Party needs to make it easier for people to participate in the democratic process, particularly the young voters that powered Sanders’ presidential campaign.

“He presented a strong case for our need to continue pursuing important policies that resonated with the American public,” said Sen. Jeff Merkley (D-Ore.), Sanders’ sole endorser in the Senate. Sanders also told senators that “we need to have a party that works a lot more with grass-roots organizing, to reach out to ordinary people who are so affected by the decisions that government makes, that we need to vastly improve how we conduct elections in our country," Merkley said.

Sanders’ relations had been somewhat frosty with the Senate Democratic Caucus after the vast majority of Senate Democrats backed Clinton’s campaign. But inside Tuesday’s lunch in the ornate Lyndon B. Johnson room just steps from the Senate chamber, Sanders earned multiple rounds of applause and standing ovations from colleagues.

Sen. Jon Tester (D-Mont.), the chairman of the Senate Democrats’ campaign arm, approached Sanders and asked for some time to discuss how the insurgent Democratic presidential candidate can aid Democratic candidates running for Senate seats in 2016.

“He absolutely would” campaign for Senate Democrats, Tester said.

Sen. Tom Carper (D-Del.) added that Sanders stressed to Senate Democrats that he has every intention of being active in the crafting of the party’s platform in Philadelphia – particularly to ensure his nearly 1,900 delegates’ voices were heard.

“He was warmly received,” said Sen. Brian Schatz (D-Hawaii). “It was, as usual, a frank discussion. He’s part of the family.”