WASHINGTON -- Sen. George J. Mitchell, with White House help, offered Democratic senators three cheaper modifications of President Clinton's health care legislation this weekend as he sought to get them to start making choices.

Each of the Mitchell variations, like Mr. Clinton's proposal, seeks to guarantee all Americans health insurance that can never be canceled and to require employers to pay some of the cost of their workers' insurance.

But each alternative would cost less than Mr. Clinton's plan, by some combination of reducing what employers would pay, decreasing what the government would pay, limiting what benefits would be provided or increasing what individuals would pay.

Mr. Clinton joined the senators at a meeting on Saturday night and urged them to move forward and to resist appeals to take only easy steps like insurance reform. He said that a strong position on health care would help their party in the November election, Sen. Paul E. Simon of Illinois said yesterday.

Mr. Mitchell, who spurned a Supreme Court nomination last week so he could concentrate on passing health care legislation, dominated the meeting and made it clear that he was taking charge of the issue, several senators said.