Donald Trump answers questions from reporters after arriving in his helicopter.

Donald Trump answers questions from reporters after arriving in his helicopter at the Iowa State Fair.

One sign of Donald Trump’s rise to the front of the pack of Republican presidential candidates is not only the flack he’s taking now from some of his fellow Republicans, but even from the Democrats.

Hillary Clinton engaged with Jeb Bush for the first few months of her campaign, when Bush was the perceived front-runner in the Republican field, but during a campaign event Sunday in Newton, Bush didn’t get a single mention from Clinton. Trump did, as Clinton talked about Wall Street reform.

“It’s not about my hair or Donald Trump’s hair,” Clinton said, to laughter. “It’s actually about what we’re going to do to take back our country.”

Later Sunday, during an appearance in Cedar Rapids, Clinton challenged Trump’s call to deport undocumented immigrants to their native countries.

“Somebody needs to ask him, ‘O.K., tell us specifically how that will happen?’ You what he says ‘Well, they’ll just go. They’ll just go just go. They’ll have to go over there and then they’ll have to stand in line and they’ll have to come back,'” Clinton said. “Eleven or 12 million people? Really?”

Bernie Sanders has staked his campaign by questioning the way the “establishment” or “billionaire class” is running the economy. This weekend during an appearance on Iowa Public Television’s “Iowa Press” program, Sanders said he “dislikes very much” the way Trump attacks people who criticize or disagree with him.

“Kareem Abdul Jabbar, for example, just wrote a statement and he attacked Kareem in a very personal way because (Jabbar) disagreed with Trump,” Sanders said. “A president cannot go around attacking everybody just because you disagree with them.”

Trump has called Martin O’Malley a “disgusting, little, weak, pathetic baby” after O’Malley apologized for saying “all lives matter” to “Black Lives Matter” activists. In response, O’Malley has called Trump an “unscrupulous charlatan.”