A questionnaire accompanying the appeal says the government could check voting registration records, "prompting fears that GOP voters might be discriminated against for medical treatment in a Democrat-imposed health care rationing system."
It asks, "Does this possibility concern you?"
Katie Wright, a spokeswoman for the Republican National Committee, said the question was "inartfully worded."
She said, however, that people should worry because government officials would have access to personal financial and medical data.
A revamped health care was one of President Barack Obama's main campaign subjects in last year's election. About 50 million of the 300 million Americans lack health insurance. Obama's Democratic Party has large majorities in both chambers of Congress, but he has said he wants backing from both parties.
"The RNC doesn't try to scare people," said Wright. "We're just trying to get the facts out on health care. And that's what we do every day."
Jon Vogel, executive director of the Democratic House campaign organization, called the opposition party's letter "shameless fear-mongering."
In a fundraising e-mail of his own seeking to raise $100,000 by Aug. 31, Vogel wrote the Republican accusation was "just a preview of the falsehoods, fabrications and outright lies Republicans will be pushing when Congress returns in September."
The allegation is the latest instance in which some critics of the health care effort have made inflammatory unfounded claims, such as conservatives who claimed the legislation would create "death panels" that they said could lead to euthanizing elderly people.
The suggestion that Republicans might not receive care is included in a "Future of American Health Care Survey" containing 13 questions, most of which are critical of the Democratic health care effort. The technique, referred to as a "push poll," is used often in political campaigns by both parties and is designed to spread negative information, not to sample public opinion.
Another question asks, "Do you believe it is justified to ration health care regardless of whether an individual has contributed to the cost of the treatment?"
The survey is accompanied by a two-page letter signed by Michael Steele, chairman of the national Republican party. The letter accuses Democrats of "moving swiftly to bring European-style socialized medicine here," but does not mention the possibility that Republicans might be denied coverage.
Wright did not immediately respond when asked who had crafted the wording of the survey questions, and which Republican officials had signed off on it. She also said she did not initially know how many of the surveys were mailed or to whom.
House Democratic legislation would give officials access to limited information about the earnings of people who apply for federal insurance subsidies to see if they qualify, said Matthew Beck, Democratic spokesman for the House Ways and Means Committee.
The question suggesting possible denial of care for Republicans was first reported by The Columbian newspaper of Vancouver, Washington.