According to the Iowa Secretary of State’s office, in 2012 85 percent of registered voters 65 and older -- the main beneficiaries of Social Security -- cast ballots compared with about half of voters under 35.   It should be no surprise then that a recent AARP survey of Iowa voters, Democrat and Republican caucus goers, showed that the vast majority consider Social Security a key campaign issue.

"When polled on the importance of candidates focusing on Social Security, the survey found that more than nine in 10 Iowa caucus goers think it is important for presidential candidates to have a plan for the future of the program. Regardless of age, more than half of all likely caucus goers think this is 'very important.'

“When asked if they have heard enough about the candidates’ plans for the future of Social Security, 51% of Democratic caucus goers said they’d like to know more about Hillary Clinton’s plans, and 38% would like to know more about Bernie Sanders’ plans. Among Republican caucus goers, 45% would like to know more about Donald Trump’s plans, and 41% would like to know more about Ted Cruz’s and Marco Rubio’s plans.”

Social Security has played a key role in Senator Bernie Sanders’ campaign as he continues to draw distinctions between his and Hillary Clinton’s plans.  Bloomberg reports: 

“Sanders wants to keep the cap on taxable income for Social Security at the current $118,500 a year for those earning up to $250,000 annually, and apply the levy on all earnings above that amount. It would mean the top wage earners would pay more to extend the solvency of the program and expand benefits by $1,300 a year for people making less than $16,000, he said. ‘That is my view, to the best of my knowledge, that is not Secretary Clinton’s view,’ Sanders told reporters on Tuesday after a campaign stop in Des Moines

“I think it’s a mistake to go in and say, ‘Here’s what I want to do,’ sort of in effect hand them your negotiating position,” Clinton told the Des Moines Register editorial board earlier this month. “I think it’s smarter to say, ‘Look, I’m never going to go along with your privatization plan. I will not go along with raising the retirement age as the answer to everything that ails Social Security, but I will work with you to try to figure out how we help those people who are most disadvantaged.”

There are also differences between the two leading GOP candidates in Iowa, Donald Trump and Ted Cruz -- at least on the campaign trail, that is.  While Trump has supported privatization and raising the retirement age, in Iowa he promises to protect Social Security and Medicare.  Cruz, meanwhile, has stated his plans to cut benefits, privatize Social Security, and convert Medicare into CouponCare very clearly.

The caucuses begin at 7 pm Central time with separate Democratic and Republican events taking place in each of 1,681 precincts across the state. The Des Moines Register will be posting results throughout the night.