Virginia Lt. Gov. Charles S. Robb, who has been accused of sidestepping controversial issues, cast the deciding vote today to pass an emotionally charged bill providing state Medicaid funds for abortions when fetuses are seriously deformed.

The vote by Robb, the likely Democratic nominee for governor this year, was needed to break a 19-to-19 tie in the State Senate on a bill that opponent argued would put the commonwealth in the position of "playing God" with gave poor women the same right tha money affords the rich.

The abortion bill had gone down by 21 to 16 yesterday, but supporters were able to have that vote reconsidered today and mustered enough votes to deadlock the measure.

That left the bill's fate in the hands of Robb, the Senate's presiding officer, who, without hesitation or comment, cast a vote that is likely to be a major campaign issue this fall.

"I think the political consequences will be damaging, but I am still very confortable with the vote," said Robb later. "If a group wanted to use a single-issue litmus test, that's the kind of issue they'd use."

Robb's likely Republican opponent, Attorney General J. Marshall Coleman, tried today to defuse the issue, saying "I can't quarrel with the Senate action." But he wouldn't predict if it will become a campaign issue this fall.

Republican Gov. John N. Dalton vetoed last year a similar abortion bill funding proposal approved by the sate Board of Health and hinted he will veto the bill.

"People have been sniping at [Robb ], saying he'd never take a stand on an issue," said Sen. Edward Holland (D-Arlington) a supporter of the bill. "There's no question he blunted that argument today. He could have ducked it."

Even Republican Sen. Ray Garland of Roanoke, another supporter of the bill, conceded Robb's vote "will be perceived as a courageous move. It will solidify liberal support for him where there would have been grave doubts. Most of the people who would have taken a hard line on the other side are generally Republican voters anyway."

Opponents of the abortion bill, however predicted that Robb would pay for his vote in the fall campaign. "He will have to answer for that," said Eva Scott (R-Amelia), an outspoken opponent of abortion.

"He will have to take the credit for the tax dollars that will be spent on this," said Sen. A. Joe Canada (R-Virginia Beach), who opposed Robb for lieutenat governor in 1977. Canada said Robb's vote "will certainly set the stage for certifying the first differences between the candidates."

Sen. C. Boucher (D-Washinton), who led the floor fight in favor of the bill, argued that its passage would save the commonwealth money in Medicaid payments since "the costs of delivery far exceed the costs of abortion."

Most of the arguments dealt with the moral issue of providing state aid for abortons. Although the Senate passed bill yesterday authorizing Medicaid payments for abortions of pregnancies caused by rape or incest. Senate opponents argued today that aborting a pregnancy because of evidence of serious deformity would allow physicians to make subjective decisions on whether an abortion was justified.

"A physician is put in the position of playing God. He can take in his hands the question of determining whether a life was worth preserving," said Sen. Adelard Brault (D-Fairfax). He called the bill "one of the worst I have seen in my 16 years in the Senate."

Sen. Richard Saslaw (D-Fairfax) labeled Brault's argument "ludicrous" and countered, "If you've got $300 in your pocket [for a legal abortion] you can already play God."

The bill, which was amended today, now returns to the House of Delegates, were easy passage is expected. It then goes to the governor.

The Senate also approved today a stringent drug paraphenalia bill designed to eliminate "head shops," which Northern Virgina officials have led the fight to condemn. Opponents of the bill complained it will provide harsher penalties for possesing drug paraphernalia than for the drugs themselves.