Chicago (CNN) Former President Barack Obama offered effusive praise of Nancy Pelosi on Tuesday as the Democratic leader faces opposition to her bid for House Speaker.

"I think Nancy Pelosi, when the history is written, will go down as one of the most effective legislative leaders that this country's ever seen," Obama said at a live taping of "The Axe Files" podcast, produced by the University of Chicago Institute of Politics and CNN.

"The Axe Files" is hosted by David Axelrod, Obama's former top strategist and a CNN political commentator.

The interview comes as both Barack and Michelle Obama return to the public spotlight after spending most of the first year and a half of Donald Trump's presidency off the stage. Michelle Obama is touring to promote her book, while Barack Obama spent the weeks before the midterm elections campaigning for Democratic candidates.

Obama's praise of Pelosi comes as a group of House Democrats who are seeking generational change in the party's top ranks argue Pelosi has become a political anchor around its candidates.

Obama said he didn't want to weigh in on the leadership fight but called Pelosi an "extraordinary partner" before complimenting her abilities as a legislator.

"Nancy is not always the best on a cable show or with a quick soundbite or what have you," Obama said. "But her skill, tenacity, toughness, vision, is remarkable. Her stamina, her ability to see around corners, her ability to stand her ground and do hard things and to suffer unpopularity to get the right thing done, I think, stands up against any person that I've observed or worked directly with in Washington during my lifetime."

Obama said instead of "performance art," what's most important are the "nuts and bolts" of governance -- "the blocking and tackling involved in actually getting things across the finish line."

"And my experience has been that Nancy Pelosi knows how to do that, and she was an extraordinary partner for me throughout my presidency," Obama said.

Obama also said in the interview that he and Trump have "contrasting visions" about the United States.

"I think what's unique about America is our aspirations to be a large, successful, multi-racial, multi-cultural, multi-ethnic, multi-religious, pluralistic democracy," he said.

"Do you think that's President Trump's vision?" Axelrod asked.

"No, obviously not," Obama said. "We have contrasting visions about what America is. And, you know, that's self-apparent. But what I would say is that the majority of Americans believe in that story. And there is power in that story."

Obama talks guns, filibusters

In the interview, Obama also detailed his frustrations with the hurdles he faced on Capitol Hill, saying he favors abolishing the Senate's 60-vote threshold to break the filibuster and advance legislation and lambasting Republicans for failing to back new gun laws.

Obama's comments came a day after a shooting at Mercy Hospital in Chicago in which three people and the gunman were killed.

He said the hardest day of his presidency was the Sandy Hook shooting.

"The angriest I was ever during my presidency was seeing Congress not doing anything about it. Completely unresponsive," Obama said.

He complained that mass shootings in the United States are followed by "this Kabuki dance of, 'We're offering thoughts and prayers,'" and then no action.

"The NRA and the entirety, just about, of the Republican Party, and some Democrats ... would just shut off any discussion of dealing with this public health crisis that does not exist anywhere else," he said.

Obama also said the Senate should abolish the filibuster, a move that would mean legislation requires just a simple majority of votes to pass.

He said his agenda was repeatedly stymied by Republicans because of the filibuster, and that he failed to turn Washington's gridlock into an issue that motivated voters.

"I'm the first to confess, you know, I was not able to give this message effectively," Obama said.

"It's just not the stuff that moved people to vote, and the other side didn't get punished for it," Obama said. "We couldn't focus enough attention on the fact that the basic norms of governance that took place for prior presidents suddenly didn't hold for us."

Obama praises Beto O'Rourke's Texas Senate run

Obama, when asked about Beto O'Rourke, praised the Democratic congressman who shattered online fundraising records and visited all 254 of counties in Texas on the way to a closer-than-expected loss to GOP Sen. Ted Cruz.

He called O'Rourke an "impressive young man who ran a terrific race in Texas."

"What I liked most about his race was that it didn't feel constantly poll-tested," Obama said. "It felt as if he based his statements and his positions on what he believed. And that, you'd like to think, is normally how things work. Sadly it's not."

He also compared O'Rourke to himself.

"The reason I was able to make a connection with a sizeable portion of the country was because people had a sense that I said what I meant," Obama said. "And that's a quality that, as I look at what I'm sure will be a strong field of candidates in 2020, many of whom are friends of mine and whom I deeply respect -- what I oftentimes am looking for first and foremost is, do you seem to mean it? Are you in this thing cause you have a strong set of convictions that you are willing to risk things for?"

When Axelrod pressed Obama on whether O'Rourke struck him as someone who fit that description, Obama said, "Yes, and I think there are others. We've got a number of people who are thinking about the race who I think fall in that same category."