Federal and state governments are entering the home stretch in the race to carry out the most important health care reform in more than four decades. The most pressing task is to establish new health care exchanges, the electronic marketplaces in which consumers will be able to compare and buy insurance plans just as they buy airplane tickets or rent cars on the Internet.

The exchanges are scheduled to start enrolling people on Oct. 1 in policies that will become effective in January 2014. It is a challenging task but not an impossible one, as long as Americans have a chance to learn how they can benefit from the coverage and from sliding-scale subsidies provided by the federal government under the Affordable Care Act.

To their shame and discredit, Republicans are trying to block efforts to inform people about the law and are using scare tactics to keep them from enrolling. The Republican mantra is that the nation will face economic and medical catastrophe — a “train wreck,” they say — unless health care reform is stopped in its tracks.

Their tactics are despicable. When Kathleen Sebelius, the secretary of health and human services, revealed that she was talking with the National Football League and other athletic organizations about ways to inform their fans about insurance on the exchanges, the two highest-ranking Republican senators wrote a threatening letter that caused the league to back off.