NORTH LIBERTY, Iowa (AP) — Democratic presidential candidates promised voters in Iowa on Saturday they would unify the party to take on President Donald Trump even as they kept up their criticism of each other and navigated the lingering divides from the 2016 campaign. About 20 miles away in Cedar Rapids, Massachusetts Sen. Elizabeth Warren updated her stump speech to include a more explicit call for unity. And Bernie Sanders insisted he would back the ultimate Democratic nominee even if it’s not him. On the eve of Monday’s Iowa caucuses, the unity pledges marked an early — and urgent — effort to avoid the divides that some Democrats say helped Trump win the presidency in 2016. After a year of campaigning, most polls show a tight race between Biden, Warren, Sanders and Pete Buttigieg, the former mayor of South Bend, Indiana. Those candidates, along with Sen. Amy Klobuchar of Minnesota and businessman Andrew Yang, crisscrossed Iowa on Saturday seeking a breakout victory that would propel them deeper into the contests that will decide the Democratic nomination.