A component of the latest Senate proposal to expand health insurance coverage is to let 55-64 year-olds purchase a policy under Medicare, the established government program for individuals 65 and older that is funded in large part by payroll taxes.
The Kaiser Family Foundation has polled for many months on the item "Expanding Medicare to cover people between the ages of 55 and 64 who do not have health insurance." As shown in this document, the percent of Americans supporting the idea has consistently been in the 70s.
Some of the provisions currently being considered in the Senate may not map exactly onto the policy implied in the survey item, however. For example, the survey's phrase "[e]xpanding Medicare to cover people..." may suggest to some respondents that 55-64 year-olds could participate in Medicare on the same basis as individuals 65 and older (i.e., with some of the costs financed by taxpayers), not that those 55-64 must "buy in" on their own (or possibly with some degree of subsidy).
Also, the qualifier "...who do not have health insurance" could be open to different meanings. It could theoretically refer to anyone 55-64 years old, as someone with employment-linked health insurance could drop it (and in that sense, not have insurance) and then purchase Medicare. Or it could refer only to people who have lacked health insurance for some length of time or with some chronicity. In the actual legislation, the segment of 55-64 year-olds eligible to purchase Medicare could be even narrower, as described in this article: "primarily those who have been uninsured for a certain amount of time, have a history of poor health or are unable to get insurance because of a preexisting condition."
Back in May, KFF issued a detailed study of health insurance coverage and health status of 55-64 year-olds. This report may be of interest to our more policy-wonkish readers.