Millions of Americans are worried about their financial security in retirement. According to one recent study, in fact, nearly half of all boomers fear that retirement will push them into poverty.

See also: Meet the 2012 GOP presidential candidates.

Such worries are not without foundation. According to a recent analysis published in the Wall Street Journal, the median household headed by a person aged 60 to 62 with a 401(k) retirement savings account can expect that account to cover less than a fourth of what the household will need to maintain its standard of living in retirement. Fidelity Investments' recent analysis of the 11 million 401(k) accounts it maintains found an average balance of just $74,900.

What's more, many other Americans are in even worse shape when it comes to their retirement savings, having no 401(k) at all, for example, or having liquidated them after losing their jobs in the recent recession.

AARP invited the six leading GOP candidates to address the issue of retirement security and three other subjects — Social Security, Medicare, and jobs and the economy. Four of the candidates (Michelle Bachmann, Newt Gingrich, Ron Paul and Rick Perry) accepted AARP's invitation; two (Herman Cain and Mitt Romney) declined.

Watch the retirement security segments of the 20-minute candidate interviews in the video player above. Dave Price of WHO-TV, the NBC affiliate in Des Moines, Iowa, interviewed the candidates on Nov. 4.