After months of rallies, speeches and debates, the U.S. primary election campaign is set to formally get under way Monday, when Iowa residents cast their presidential preference at caucus sites across the Midwestern state.
Ahead of the crucial, first-in-the-nation 2016 vote, opinion polls in Iowa revealed a tantalizingly close race for both the Republican and Democratic party nominations, with non-establishment candidates continuing to show resiliency.
On the Republican side, real estate developer Donald Trump maintains a slight lead over Texas Senator Ted Cruz, who appears to have made several missteps in the lead-up to the Iowa caucuses.
For the Democrats, the race seems to be a virtual tie between former secretary of state Hillary Clinton and independent Vermont Senator Bernie Sanders, the self-declared democratic socialist.
WATCH: VOA Snapshot of the Iowa Race – Voters
Candidates in both parties made a final sprint through Iowa Sunday, holding events in every corner of the state, stepping up attacks on rivals and making last-minute appeals to key voter groups.
Sunday morning TV network news shows also were a key platform. On ABC’s This Week, Trump tore into his main challenger Cruz, calling him a “total liar” and a “nasty guy.”
“Here’s a guy with all these senators, (but) not one endorsement of Cruz, because he’s a nasty guy,” Trump said. “You can’t run a country that way. It will be a total mess.”
Trump also continued to raise questions about whether Cruz is eligible to run for president, because he was born in Canada to a Cuban father and an American mother.
Cruz shot back, challenging Trump’s conservative credentials on issues such as health care, and accusing Trump of running an immature campaign.
“I think the people of Iowa deserve more,” Cruz told CNN’s State of the Union. “I think the American people deserve more than just a battle of petty insults. And so I don’t intend to play that game."
Cruz’s chances to win the Iowa caucuses are seen as slightly diminished after he suffered a shaky debate performance last week. His campaign also was on the defensive after sending out a campaign flier that seemed to threaten voters if they did not show up to vote.
WATCH: VOA Snapshot of the Iowa Race – Republicans
Trump and Cruz are both trying to portray themselves as political outsiders. They also are both competing to attract evangelicals, which make up a large percentage of Iowa Republicans.
Trump on Sunday headed to church in Council Bluffs with his family. The real estate magnate also appeared at campaign events with Jerry Falwell Jr., the prominent evangelical leader and president of Liberty University.
Sanders attacks Clinton on emails
Meanwhile, Bernie Sanders showed an increased willingness to raise questions about the scandal over Hillary Clinton’s use of a personal email server during her time as secretary of state.
After months of refusing to make the issue a point of attack on the campaign trail, Sanders told CNN that the controversy is a “very serious issue.”
When asked whether he thought Clinton did anything wrong, he replied: “Nope, nope. That is not, I think, a fair assessment. That is, I think, a very serious issue. There is a legal process taking place. I do not want to politicize the issue. It is not my style.”
The U.S. State Department, which has been releasing Clinton’s emails in batches, on Friday said it would not publish a series of the messages because they contained classified information.
WATCH: VOA Snapshot of the Iowa Race – Democrats
Her critics say the use of the private, relatively unprotected email server put U.S. national security at risk, and may even have violated some laws.
Clinton has said she did nothing wrong and that the emails were not marked classified at the time they were sent.
On Sunday, Clinton repeated her stance that the emails should be made public, and she slammed her Republican critics for focusing on the issue.
“It’s clear they’re grasping at straws,” Clinton told ABC.
The Sanders and Clinton campaigns on Sunday also reached an agreement with the Democratic National Committee (DNC) to hold additional debates, something many in the party had wanted.
The DNC said the next officially sanctioned debate will be held Thursday in New Hampshire, where Sanders has a substantial double-digit lead over Clinton.
WATCH: Candidates make final pitches before Iowa caucus
New Hampshire is the next focus for presidential hopefuls. The northeastern state holds its primary election February 9.
Iowa storm coming?
But for now, all eyes are on Iowa, where a major snowstorm is expected to hit about the time residents gather at caucus centers to vote late Monday.
The storm could significantly impact voter turnout, providing an advantage for better organized campaigns, or those with more passionate supporters.
“I think the conventional view here is that if there’s high turnout, that is great news for Bernie Sanders,” says Kathie Obradovich, a political columnist for The Des Moines Register.
In the end, the biggest wild card in the caucuses may come down to the weather, Obradovich told VOA.
“When it’s a small turnout event, anything can happen. So, bad weather would add to the uncertainty of what happens on caucus night,” she said.