IOWA CITY, Iowa - Though it seemed to begin the moment President Obama finished taking the oath at his second inaugural, the 2016 presidential election finally gets underway Monday when the first real votes are cast in the Iowa caucuses.

Democratic and Republican candidates on Sunday raced across the state, from the Mississippi to the Missouri, exhorting their supporters to turn out for the caucuses while also framing expectations to put them in the best possible light no matter what happens in the voting.

Republican Sen. Ted Cruz of Texas closed out his Iowa campaign with rallies in Iowa City, Davenport, and Des Moines, alongside talk-show host Glenn Beck and Phil Robertson, the patriarch of the reality-TV show Duck Dynasty.

Donald Trump, the New York real estate developer and GOP front-runner, continued to woo evangelical Christian voters with two rallies in the company of Liberty University president Jerry Falwell Jr., who has endorsed him.

"If we stand together, as principled conservatives, we will win . . . and pull this country from the abyss," Cruz told 500 cheering supporters in a pole barn at the Johnson County Fairgrounds in Iowa City. "The time for all that media noise has passed. This is our time; this is your time. We can't get fooled again."

Trump was confident. "We're going to win; we're going to win," he said at a middle school gym in Council Bluffs. "We're leading everywhere."

He told his crowds to ignore everything - even a snowstorm forecast to strike parts of the state Monday night - and make sure to vote for him in their caucuses.

Both parties' contests are tight.

The respected Des Moines Register/Bloomberg Politics Iowa poll released Saturday showed Trump receiving 28 percent of the support of likely caucus-goers and Cruz receiving 23 percent. Sen. Marco Rubio of Florida was overwhelmingly the third choice, at 15 percent.

On the Democratic side, former Secretary of State Hillary Clinton was virtually even with Sen. Bernie Sanders of Vermont, 45 percent to 42 percent. The margin of error for both samples was plus or minus 4 percentage points.

Sanders said the country and the world would be watching the state "to see whether or not Iowa is prepared to move this country away from establishment politics and establishment economics" toward a political revolution against systems rigged for the rich.

"Monday night could be an historic night for this country," Sanders told a crowd estimated at 655 people at a convention center in Waterloo, about 130 miles northeast of Des Moines. "We can make history."

Sanders, 74, a self-described democratic socialist, addressed possible concerns that he would get trounced in a general election against the Republican nominee.

"What everybody here knows is Republicans win elections when the American people are demoralized and when they do not come out to vote," he said.

"We win when large numbers of people come out to vote," Sanders said, adding that "the excitement and the energy is with our campaign," not Clinton's.

After noting that the main super PAC backing Clinton announced this weekend that it had about $45 million in the bank, Sanders said to applause, "We made the announcement, of course, that we had raised zero dollars from our super PAC."

At a high school in Council Bluffs, Clinton told a crowd of more than 500: "We are getting down to the last hours. I want you to hold me accountable for delivering for you."

She added a dig at Sanders: "I don't want to overpromise and under-deliver."

Clinton made two stops in western Iowa and campaigned with her husband, former president Bill Clinton, and daughter, Chelsea.

Sanders, who promises free public college tuition, a single-payer health-care system, and paid family leave, among other things, argues that Clinton is too timid. She has been pressing the case that Sanders is unrealistic.

Iowans will gather at schools libraries, homes, taverns, and even a grain elevator or two to make their choices known.

Caucuses are private party meetings that elect delegates to county conventions, which elect delegates to district and state conventions.

Republicans use paper ballots after supporters of the various candidates speak. Democrats split into preference groups, physically: Clinton people in one corner, Sanders people in another. A candidate has to have 15 percent of those present to be "viable," which has focused interest on the possible second choices of supporters of former Maryland Gov. Martin O'Malley, who is polling at about 3 percent.

Republicans turned out roughly 120,000 people to the caucuses in 2008 and 2012. Democrats had just over 124,000 in 2004, but in 2008, the efforts of Barack Obama - as well the rest of a competitive field - helped nearly double that number, with nearly 240,000 showing up.

Most Republicans expect a higher turnout in 2016 than the last two caucuses, while Democrats largely think they'll beat their 2004 number, but not hit the 2008 high.

215-854-2718@tomfitzgerald

Staff writer Andrew Seidman contributed to this article, which includes information from wire services.