Tied with rival John Kerry (search) in the crucial swing state of Missouri, President Bush (search) is defending his new Medicare prescription drug discount cards (search) that are coming under increasing criticism from Democrats.

In the 18th trip of his presidency to Missouri and the fifth this year, Bush says the program that started June 1 marks a major step forward in ensuring affordable medicine vital to the health of the elderly. He takes that message Monday to an audience of 500 health care professionals and senior citizens in the Kansas City suburb of Liberty.

Some Democrats say the program has major problems. The number of seniors signing up for the cards has been lower than expected. The sign-up process is "hopelessly confusing," said Senate Democratic Leader Tom Daschle of South Dakota. Kerry's campaign says 20 of the 73 companies selected by the Bush administration to provide the cards have been involved in allegations of fraud, 11 of them for defrauding Medicare.

Underscoring the concern, Sen. Jim Talent and Rep. Kenny Hulshoff, both Missouri Republicans, conducted a town meeting Monday with seniors in the university town of Columbia, another area of Missouri that is critical to Bush's efforts to carry the state as he did four years ago.

The Bush administration says the cards will save their users up to 18 percent on average on retail prices for brand-name prescription medicines. Some 7.3 million Medicare recipients could get cards, including 4.7 million with incomes low enough to receive $600 from the federal government this year and again in 2005 to pay pharmacy bills.

About 2.4 million of the 3 million-plus enrollees to date are members of health maintenance organizations (search) who were enrolled automatically in their HMOs' card programs. Another 400,000 low-income Medicare recipients, who already receive help with their prescriptions, are in the process of being enrolled by state drug assistance programs.

Some Democrats want to reduce the number of cards available to three for each region of the country, require card sponsors to keep discounts at least as deep as they were when a client signed up, and prohibit sponsors from dropping medicines.

White House spokesman Trent Duffy says "we do not want to limit choices" because a greater number of cards will contribute to a competitive environment that will lower prices. He said millions of people are signing up for cards.

The discount cards are intended as a temporary measure until prescription drug insurance under Medicare begins in 2006. In theory, they allow individuals with no prescription drug insurance to benefit from lower prices available through group purchasing.

Recent polling shows Bush and Kerry tied in Missouri, and political experts say the race in the state, as in the rest of the nation, will likely turn on voter sentiment on the war in Iraq (search) and the economy.