JUDY WOODRUFF: It is safe to say voters in the Hawkeye State are by now narrowing their keen political sights on the race for the White House. Iowa will once again play an outsized role in a presidential election, when, in a little more than four months, it will host the first nominating contest of the season. Lisa Desjardins reports on the latest spring among the Democratic hopefuls.
LISA DESJARDINS: In Iowa, the pressure and the stakes couldn't be higher. Saturday, Democratic candidates angled for attention at the annual Iowa Steak Fry, grilling meat and veggie burgers, dancing with supporters and addressing thousands of caucus-goers.
SEN. BERNIE SANDERS (I-VT), Presidential Candidate: In this unprecedented moment in American history, we need to run an unprecedented campaign.
LISA DESJARDINS: And it comes as the presidential pack faces some shifting realities. The new Iowa poll from The Des Moines Register and CNN shows a change. Massachusetts Senator Elizabeth Warren has stepped into first place in the Hawkeye State, two points ahead of former Vice President Joe Biden. Vermont Senator Bernie Sanders, while still in third, is now 11 points behind the lead. Warren played down the results Sunday while picketing with striking auto workers in Detroit.
SEN. ELIZABETH WARREN (D-MA), Presidential Candidate: I don't do polls. We are still months away from the Iowa caucuses and the first primary elections. We are on this picket line today to say that we're going to make this American work for everyone.
LISA DESJARDINS: But Iowa numbers are clearly on others' minds. Senator Kamala Harris, running in fifth in the poll there, is changing gears, announcing more focus on the Iowa. In South Carolina Sunday, our Yamiche Alcindor spoke to Harris about that strategy.
SEN. KAMALA HARRIS (D-CA), Presidential Candidate: I am really excited about where we are. Our strategy was always to invest in Iowa early, which we did, and to ramp up after Labor Day, which we're doing.
SEN. CORY BOOKER (D-NJ), Presidential Candidate: Hello, Iowa!
LISA DESJARDINS: Others are more blunt about their situations, like New Jersey Senator Cory Booker. His campaign released a memo it said told the unvarnished truth, that he needs to raise $1.7 million by the end of the month. Booker has the most endorsements in Iowa, but his team said, without the cash, he will have to leave the race.
SEN. CORY BOOKER: Grow or get out.
LISA DESJARDINS: This all in the shadow of allegations that President Trump pressed Ukraine's president to investigate Biden. A chorus of Mr. Trump's opponents criticized him over that this weekend. South Bend Mayor Pete Buttigieg:
PETE BUTTIGIEG (D), Presidential Candidate: It's extremely disturbing. In fact, if true, they represent a betrayal of the United States.
LISA DESJARDINS: Former HUD Secretary Julian Castro:
JULIAN CASTRO (D), Presidential Candidate: It's time for Congress to do its job and impeach Donald Trump.
LISA DESJARDINS: And Biden himself.
JOSEPH BIDEN (D), Presidential Candidate: A serial abuser, that's what this guy is. He abuses power everywhere he can. And he sees any -- if he sees any threat to his staying in power, he will do whatever he has to do. But this crosses the line.
LISA DESJARDINS: From the right, Republican opponent and former GOP Massachusetts Governor Bill Weld went even further.
BILL WELD (R), Presidential Candidate: That is not just undermining democratic institutions. That is treason. It's treason, pure and simple.
LISA DESJARDINS: Still, the campaign goes on. The weekend included an LGBTQ forum in Iowa, more striking autoworkers. Biden joined this group in Kansas city. And, yesterday, Sanders showed he wants a broad map, meeting with the Comanche tribe and holding a rally in Oklahoma. For the PBS NewsHour, I'm Lisa Desjardins.