A Senate committee that only a day before had slashed millions of dollars from Gov. Harry Hughes' proposed Medicaid budget veered in the opposite direction today and passed a bill that would raise welfare payments by 10 percent a year starting in 1982 -- far above the level Hughes says that state can afford.

"I used to picture the welfare recipient as a fat cat sitting in a Cadillac, but I've learned. I know it's women and children and they're desperate. I think we have a moral obligation to address this issue," said Sen. Francis Kelly (D-Baltimore County), a conservative who supported the Medicaid cut but pushed the welfare increase today.

Kelly and other supporters of the increase promised they would also find a way to pay for the added welfare payments, which would total $16 million the first year.

The move was the latest in a series of changing signals from the Senate committee, which in the last week has stripped down Hughes' proposed budget, then restored key items and then changed course again to cut out some of the programs Hughes fought hardest to keep.

The continual shifts have backed Hughes into a corner, at a time when he was already fighting up hill to rally support for his just-announced $58 million tax and spending package.

He and his aides had expected the Senate committee to restore several major programs cut by the House earlier this month -- particularly the $15 million Medicaid cut, which the state health department secretary calls "tragic." After initially refusing to do so, the Senate committee began considering several major restorations. Then yesterday, it reversed course.

Now, Hughes will have to take his budget battle to the Senate floor tomorrow. If he fails, the cutbacks will take effect, since the House approved most of the same cuts advocated by the Senate committee.

After lobbying several interest groups all day on behalf of his $58 million package, the governor turned his efforts tonight to the Senate, trying to enlist its members in his fight to undo some of the major cuts. At 6 p.m., when today's session ended, he called more than a dozen Seante leaders and members of the rank and file to his office.

At the top of the governor's list are the Medicaid cut, a $500,000 reduction in a welfare program unaffected by today's vote, two dozen Health and Mental Hygiene Department jobs and cut in prison health care that Hughes' aides contend will put Maryland in violation of court orders.

It appeared that some Senate leaders would join the governor in his floor fight with the committee, although the leadership had promised last week to endorse whatever actions the budget committee took. That solidarity began to erode, however, when a bloc of seven senators teamed up yesterday to push through last-minute cuts in welfare, health care, the University of Maryland budget, and the $15 million slash in Medicaid.

"Nothing's singed in blood," said Sen. Harry McGuirk (D-Baltimore), chairman of the Economic Affairs Committee. "There will be serious attempts to change some of the committee's actions." Meanwhile, the same Senate committee threw a major obstacle today into the path of Hughes' $58 million package to aid education and transportation and give state employes a $500 raise. Committee chairman Laurence Levitan canceled a vote on the proposed gasoline tax that is to finance much of the package, after polling his committee and concluding that it could not pass.

The committee's vote today to increase welfare payments also runs against Hughes' policy, since the governor omitted a welfare increase from the $58 million package he unveiled on Monday and instructed his aides to testify against the bill.

The bill affects only welfare recipients covered under the Aid to Families with Dependent Children Program, which now provides $326 a month for a family of four -- one of the lowest payments outside the Sunbelt states. I would gradually raise the payment each year, beginning in 1982-83, until it brings the families to a minimum level of subsistence, set by the state. Fiscal analysts say the increases will cost $96 million by 1986.

Some senators accused their colleagues on the committee of grandstanding on the welfare issue, since the bill will automatically die unless the panel also passes a measure to fund it. But the bill's supporters said they play to vote out another measure to repeal certain sales tax exemptions in order to pay for the increase.