Ken Thomas ?and Scott Bauer

MANCHESTER, IOWA: As if hearing Marco Rubio’s footsteps creeping up on him, Ted Cruz directed much of his final advertising against the Florida senator in the frenzied weekend prelude to the Iowa caucuses, feeding a Republican feud that turned increasingly bitter before voters have their first say in the 2016 presidential race.

Considered to be vying with front-runner Donald Trump for Iowa victory Monday, Cruz denounced the next in line, according to polls, sharply challenging Rubio’s conservative credentials on the airwaves while ignoring him face to face with Iowans. One ad said darkly of Rubio: “Tax hikes. Amnesty. The Republican Obama.”

“The desperation kicks in,” Rubio said in response to Cruz. “From my experience, when people start attacking you it’s because you’re doing something right.”

On the Democratic side, Bernie Sanders implored Iowa supporters Saturday to get on their feet in two days and convert their monthslong infatuation with his upstart campaign against Hillary Clinton into actual votes. That call to action was echoed by Democratic and Republican hopefuls alike as they worked to motivate Iowans to attend the caucuses.

Trump, the showman of the Republican race and its front-runner, made a dramatic entrance to a Dubuque rally as his jet flew low over a hangar half-filled by the waiting crowd and music played from the movie Air Force One. There was more drama inside, as a small group of protesters interrupted him and Trump joined the crowd in chanting “USA” to drown out the discord.

He asked security to “get them out” but “don’t hurt them.”

Iowa offers only a small contingent of the delegates who will determine the nominees, but the game of expectations counts for far more than the electoral math in the state. Campaigns worked aggressively to set those expectations in their favor (meaning, lowering them) for Iowa, New Hampshire and beyond.

Asked whether Rubio could win or come second, his senior strategist Todd Harris laughingly responded with an obscenity and said the goal in Iowa is third, behind the flamboyant Trump and the highly organized Cruz.

“There’s no question we are feeling some wind at our back,” he said. But, he added: “It’s very hard to compete with the greatest show on earth and the greatest ground game in Iowa history. So we feel very confident that what we need to do here is finish a strong third.”

With that, he tried to set expectations so that if Rubio finishes better than third, it can be proclaimed a great performance.

In the last major preference poll before the caucuses, Trump had the support of 28 percent of likely caucus-goers, with Cruz at 23 percent and Rubio at 15 percent. The Iowa Poll, published by the Des Moines Register and Bloomberg, also found Clinton with 45 percent support to Sanders’ 42 percent. The poll of 602 likely Republican caucus-goers and 602 likely Democratic caucus-goers was taken Tuesday to Friday and has a margin of error of plus or minus 4 percentage points.

The Clinton and Sanders campaigns reached agreement to hold a debate in New Hampshire this week and three more in the spring, supplementing a light debate schedule that has favored weekend slots when fewer people watch TV. The tentative New Hampshire event is to be held Thursday, giving voters a chance to see the field debate before the state’s primary Feb. 9.