Hillary Clinton dialed back her biting attacks on rival Bernie Sanders on Saturday, refocusing on Republicans and her own experience in President Barack Obama's administration as she launched her closing argument to voters in Iowa.

Sanders' rise before the Iowa Democratic caucuses jolted Clinton, leading her to launch a flurry of criticism against the Vermont senator, whom she views as unelectable and a proponent of unrealistic policies. But the heated rhetoric has worried some Clinton supporters, who fear it could turn off some undecided voters.

The former secretary of state took a softer tone Saturday, to Sanders as her "esteemed opponent." She put aside most of her direct criticism of Sanders, except on gun control as well as on health care, as she warned against the senator's call for a government-paid system.

Clinton did draw implicit contrasts with Sanders throughout her remarks, particularly on national security experience.

But unlike her appearance in Iowa last week, when she said Sanders "hasn't really thought it through" on foreign policy, she told detailed stories about her own experiences making big decisions in the Situation Room while serving as Obama's secretary of state.

"This is one of the biggest parts of the decision as you head toward Feb. 1 that I want you to keep in mind," Clinton said, telling voters that they're "not just picking a president, but a commander in chief."

Clinton and Sanders were shadowing each other across eastern Iowa on Saturday, holding events in the same areas within hours of each other. Both candidates planned to spend most of the next week in Iowa as they seek to start off the primary voting with a win.

Sanders has suggested that Clinton is the product of a political system that marginalizes the middle class. He's been particularly sharp in highlighting the high-dollar speaking fees she received from the same big Wall Street banks he wants to break up.

Sanders, an independent who aligns with Democrats on Capitol Hill, has far less backing among the party establishment than Clinton. He's counting on strong support in Iowa in college towns and liberal strongholds, though he's making a late push in smaller cities and rural areas as well.

For Sanders, an upset victory in Iowa would put him in position to win both of the first two voting contests. He's consistently led in preference polls in New Hampshire, which borders his home state.

Only one Democrat has ever won the nomination without winning at least one of the first two states: Bill Clinton during his 1992 White House run.

Clinton said she would be eager to get her husband's advice, particularly on economic policy, if she becomes president. She also ran through some of the suggestions she's received for what the former president's title might be if they returned to the White House in 2017.

"First gentleman. First dude," she said as the crowd roared with laughter. "First mate -- what do you think?"