Barack Obama told a rapturous crowd of Democratic party faithful in southern California on Saturday it was time to “kick off the bedroom slippers” and get to work, to ensure the party retakes the House of Representatives after November’s midterm elections.

Having seized the limelight with an electric speech in Illinois on Friday in which he denounced the divisiveness and resentment of Trump-era politics, the former president urged campaigners in key California districts to engage with independents and disaffected Republicans to promote a concept of government less cynical and more responsive and accountable to voters.

“I cannot help but feel optimistic,” Obama said, “because if you are doing what you need to do, if you are active, involved, hopeful, optimistic, energized, fearless… I am absolutely confident these candidates are going to win. I am absolutely confident that Washington will start working better.”

Obama’s sallies drew a response from the vice-president, Mike Pence telling Fox News in an interview to be broadcast in full on Sunday it was “very disappointing to see President Obama break with the tradition of former presidents, and become so political”.

“The truth,” Pence claimed, was that “the American people in 2016 rejected the policy and direction of Barack Obama when they elected President Donald Trump.”

Obama’s Saturday appearance was an invitation-only affair at the Anaheim Convention Center, a stone’s throw from Disneyland and barely half an hour’s drive from four of the Republican-held suburban districts the Democrats are most anxious to win in November.

Obama spoke to supporters and campaign staff for seven candidates in all – each running in a district with a Republican incumbent but which voted for Hillary Clinton over Trump.

Where there’s a vacuum in our democracy, when we’re not participating … other voices fill the void Barack Obama

“The stakes are high in this election,” Obama said. “If we don’t step up, things can get worse. Where there’s a vacuum in our democracy, when we’re not participating, when we’re not stepping up … other voices fill the void.”

He touched on policy issues likely to be central to many California campaigns – healthcare, education, a living wage, financial solvency for retirees, global warming and the integrity of California’s natural beauties. But he said the most important thing was to reaffirm the country’s shared values and bring people together.

“There’s no set of issues we can’t solve if we’re working together and we’re true to traditions that are best in America,” he said. “People are saying, Enough is enough, we’re going to kick off bedroom slippers, we’re putting on our marching shoes.’”

Democratic operatives believe they need to win at least four of the seven races showcased at the rally if they are to stand a chance of attaining the 23-seat net gain they need to take back the House. The seven include seats being vacated by two powerful but retiring Republicans – Darrell Issa, a former House oversight committee chair, and Ed Royce, chair of the foreign affairs Committee – that are viewed as particularly ripe for the taking.

Also seen as particularly vulnerable is Dana Rohrabacher, known for his close ties to Russia. He was recently featured in Sacha Baron Cohen’s TV show Who is America? speaking out in favor of arming schoolchildren. Rohrabacher’s opponent, Harley Rouda, took the opportunity to paint Rohrabacher as both gullible and extreme. Rohrabacher countered that the show was nothing but a “sick fraud”.

Winning all seven seats appears eminently possible; a particularly good showing might extend to three or four more seats in the Golden State currently scored as leaning Republican.

Greater stretches would be seats with problematic incumbents such as Duncan Hunter, a San Diego-area representative currently under indictment on corruption charges, and Devin Nunes, the controversial chair of the House intelligence committee who is seen as an apologist for Trump who has actively resisted attempts to investigate Russian interference in the 2016 election.

Obama reminisced about two previous visits to Anaheim, one a trip to Disneyland as an 11-year-old and another as a student when he wandered into the theme park after a Kool & the Gang concert and was thrown out for smoking. Back then, Anaheim and surrounding Orange county was one of the most conservative areas in the country.

Now, changing demographics and a distaste for Trump’s brand of conservative politics are rapidly turning the county blue. Obama said it was not enough to rely on shifting tribal allegiances: candidates and their supporters needed to reach across the political spectrum.

“I want you to talk to independents,” he said. “I want to reach out even to some Republicans, who harken back to the values of a guy called Abraham Lincoln … who say to themselves, ‘I don’t recognise what’s going on in Washington right now, that’s not what I believe. That’s not who we are as a people, as a country.’”

The crowd cheered and hollered, breaking into periodic chants of Obama’s presidential campaign slogan: “Yes we can! Yes we can!”

“Are you ready to get to work?” the former president asked three times, in a rousing crescendo. The answer each time: a resounding yes.