And yet, I still don’t believe her.

(CNN) — First lady Michelle Obama, making campaign stops in Nebraska and Iowa on Monday, boosted her husband’s credentials while appearing to make small contrasts with his likely rival Mitt Romney, lauding President Barack Obama’s core set of values and relaying stories of his modest upbringing.

Appearing alongside Warren Buffett in Omaha, Nebraska, Michelle Obama touted the White House-backed provision named for the billionaire investor, which would place a minimum 30% tax on Americans making more than $1 million a year. The “Buffett Rule” was blocked in the Senate last week.

In explaining the president’s commitment to helping Americans who are struggling, the first lady harkened back to Barack Obama’s upbringing.

“See, believe me, what you have to know is your president, Barack, he knows this,” Michelle Obama said. “He knows this all too well. He understands these issues because he’s lived them. He was raised by a single mother who struggled to put herself through school and pay the bills.”

While not mentioning Romney explicitly, her reference to the economic struggles of her husband drew an implicit comparison with the Republican candidate, who has built a fortune estimated to be between $85 million and $264 million. Romney’s father also enjoyed financial success, becoming the president of American Motors and then the governor of Michigan.

Many political observers have questioned whether Romney, given his wealth, will be able to connect with middle class voters. In her speech Tuesday, Michelle Obama emphasized her husband’s ability to connect, given his experience.

Believe me, Barack knows what it means when a family struggles,” Obama said. “Believe me, he knows what it means when someone doesn’t have a chance to fulfill their potential, and how much that hurts. Those are the experiences that have made him the man and the president he is today.”