(CNN) Former President Barack Obama met with House Democratic freshmen in Washington at an event Monday night hosted by House Speaker Nancy Pelosi, and Obama had some advice for the new class of lawmakers who've been making headlines since before they were sworn in.

According to a source in the room, Obama told lawmakers it was important for them to identify issues that they care enough about that they'd be willing to lose their seat for them, citing the tremendous legislative hurdles faced by his signature piece of domestic legislation: the Affordable Care Act . Obama cited the Democratic House members who lost their seats in the 2010 midterm election, following the passage of the law more commonly referred to as Obamacare, which has grown widely in popularity since its passage in 2010.

Democrats are celebrating Tuesday the ninth anniversary of the Affordable Care Act, coming at the same time that President Donald Trump's administration appears to have not given up on his campaign pledge to repeal and replace Obamacare. In a filing with a federal appeals court, the Justice Department said Monday it agreed with the ruling of a federal judge in Texas that invalidated the Obama-era health care law, a dramatic reversal.

According to the source, discussion of Attorney General William Barr's summary of special counsel Robert Mueller's report did not come up during the meeting with freshmen Monday. Neither did impeachment, as some House Democrats -- most notably Rep. Rashida Tlaib of Michigan -- have pushed for.

Obama did however bring flowers for Pelosi, whose birthday is Tuesday.

"The reason I love Nancy is because she combines a passion for doing what's right for our country and our kids, along with a toughness that can't be matched on the Hill," Obama said, according to the source.

In his comments to House freshman, Obama offered advice that spoke to the complicated issues lawmakers face.

The former president emphasized the importance of talking to people who don't agree with you -- but cautioned against chasing phony bipartisanship in this era. He noted just how far right the Republican Party has shifted in a relatively short time. He noted that the late GOP Sen. John McCain, whom Trump has often criticized, was for cap-and-trade, anti-torture and supported closing the Guantánamo Bay Naval Station detention facilities.

Without getting into specifics, Obama also said Democrats shouldn't be afraid of big, bold ideas -- and that it's good to re-imagine some of our social institutions and to update them for the new economy. But Obama also said the party needs to think practically and in the nitty-gritty about how those big, bold ideas will work and how you pay for them.

He also said the most important thing to focus on out of the gate is constituent services. At its heart, good casework and constituent services are about respecting the people who you work for and making them feel seen, heard and recognized, Obama said according to the source.

Obama also said young people have a finely tuned BS detector and can tell when an elected official really cares about them -- which is why so many young people turned out to vote for members of this freshman class.

Rep. Mary Gay Scanlon of Pennsylvania told CNN it was a nice welcome to Washington from the former president.

"It was just very old school Washington and the new members," she said. "It was just a nice pause amidst chaos."