Prince George's County Executive Parris Glendening's plan to consolidate offices involved in child support collection and enforcement ran into substantial opposition yesterday when State's Attorney Arthur A. Marshall Jr. told the County Council that the proposal is "ill-founded" and one he is willing to challenge in court.

Marshall and employes from the child support division of his office testified at yesterday's council hearing that any consolidation should place child support under his control rather than under the jurisdiction of the county executive's office, as has been proposed.

The support division provides legal representation to clients involved in child support cases. The Circuit Court, the sheriff's office, the Department of Social Services and the state's attorney's office all play related roles in the child support process.

Glendening's recommendations on child support were announced when he released his budget proposals March 28. It followed by three weeks a report by a task force that assailed the current system as "slow, uncommunicative, confusing, and . . . hostile." In his remarks, Marshall did not refute those findings, but he repeatedly challenged the task force's conclusions.

"They're doing it in a very poor way, they're going to hurt the people we serve," he added.

"The first notice I had of the taking of that portion of my office was when the budget was sent down by Mr. Glendening," Marshall said.

A succession of Marshall's employes, some tearfully, told council members that they had never been consulted by task force members about the operation of their office. Marshall said that 24 full- and part-time employes now work in the office under the terms of a contract his office executes with the state.

"We are more or less being forced not to work for Mr. Marshall," said Sandra Heaton of Upper Marlboro. "Mr. Marshall is our boss and we're very devoted to him."

Council member Jo Ann T. Bell, who chaired the child support task force, said she was "disappointed and shocked" at the employes' response. Other council members pointed out that no employes of other departments affected by the proposed change had complained about the consolidation.

"If someone is playing politics and misinforming the people, those types of things need to be aired ," said council member Floyd Wilson.

Council member Sue V. Mills also hinted that the source of the dispute over the task force findings was a political turf battle.

"Those that are in favor of the creation of the new department have not proven why," Mills said in a general discussion. "Can you prove to me that it has nothing to do with the 1984 elections?"

Mills' comment, which drew applause from the audience, was an apparent reference to the state's attorney's unsuccessful judgeship campaign last year. Glendening supported other candidates in that contest.

Circuit Court Judge William H. McCullough spoke on behalf of the consolidation proposal yesterday, adding that the state's attorney's office has been voluntarily "leaving itself out" of the process.

The council voted to delay final action on Glendening's executive order until next week. If the council does not act on the matter before June 4, it will become law automatically.

In other action yesterday, developer Loren Simkowitz told the council that he will notify it of any future rent increases on properties he owns that have been renovated with the aid of tax-exempt financing authorized by the county.

Simkowitz, who runs the Bethesda-based Monacle Management firm, operates more than 4,000 units of rental housing in the county and received nearly $24 million in low-interest financing authorized by the County Council last year to renovate two apartment complexes.

Council members, responding to complaints that they have since received from residents of those complexes, recently have sought to place some controls over the 30 to 60 percent rent increases that Simkowitz imposed.

Yesterday, the council was advised by county housing and legal staff that they have no such power over developers such as Simkowitz. Simkowitz has since partially rolled back some of the rent increases after discussions with county housing officials, and he said he loses $20,000 a month on the apartments as a result.

But council members said afterward that they are frustrated at their inability to effectively reprimand landlords who they believe are not living up to the promises they made when requesting county backing.

"We don't want to be caught in a situation where the tenants are looking to us for protection and there is none," council member Hilda Pemberton said.

"I for one am not going to vote for one more such loan," added Mills.