The evening was billed as a joint event, but it was evident from attendees that Sanders was the main draw. Three hours before it kicked off, for example, many "Feel the Bern" T-shirt-wearing folks had lined up outside the venue, the Louisville Palace.
Jane Peters, a retired education official, echoed Olin's sentiments. "I came out in support of Bernie," she said. "He has to be a leader. We need a leader badly, and I think he is the one."
After the November election, voters wondered if the Democratic Party would embrace Sanders and his fiery brand of progressive politics. During the presidential primaries, Sanders and his team were often pitted against the party apparatus. He ran in part on a platform calling for major changes to the party's policies, operations and structure, and the fighting between his team and the party's top brass often boiled over.
But now he and his team are working closely with the newly elected Perez, allowing him and local Democrats to appear before crowds that only Sanders can draw — and deciding on the look and feel of events around the country.
The packed rally Tuesday night was just the second that Sanders and Perez have scheduled together this week in battleground and red states across the country, including Texas, Nevada, Nebraska and Utah. Sanders' staff organized much of the trip, down to the music.
Sanders still does not call himself a Democrat. During an interview with ABC News before the rally Tuesday night, he proudly said he was "the longest-serving independent senator in U.S. history."
He said his road trip this week with Perez was not about sending a message of unity but rather about focusing attention on the issues and encouraging voter participation. "It's not about a message. What I'm trying to do — and I've been doing this for a number of years in a variety of ways — is to revitalize American democracy, to create a political system that is not dominated by billionaires and large corporations but bring working people into the political process.
"We're trying to revitalize American democracy and rebuild the Democratic Party, making the Democratic Party into a grass-roots party, in which decisions go from bottom on up and not the other way around."
Still he said he is "thrilled" that the party is making some of the changes.
“We are seeing a lot more people involved in the political process," he said. "We're seeing a lot more people in general getting involved in the political process, and I think that is a good thing."
Perez praised Sanders' ability to energize voters. Sanders did not shy away from discussing reforms he still thinks the party needs to make.
"We need to transform the Democratic Party," he told the crowd, slipping into familiar lines from the campaign. "We need to make the Democratic Party not just a party of the East Coast and the West Coast but a party for all 50 states."
"I am really glad you reacted like that way," he said when the cheering died down. "I think it is the single biggest electoral advantage we would have in next year's election if we as a party embraced single-payer."