PHOENIX — A $9.21 million spending plan approved Tuesday by the state Senate could face a gubernatorial veto because it underfunds state universities, an aide to Gov. Jan Brewer said.

Andrew Wilder, the governor’s spokesman, said Brewer wants more additional money for state universities than the $2.5 million bump in the Senate package.

He said Brewer is also not satisfied with a Senate proposal to give district-run charter schools only an extra $600 a year per student in state aid — a total of $16.5 million, half the amount approved by the House.

On another front, Wilder said his boss is not willing to accept language inserted into the budget by Senate President Andy Biggs saying the Legislature will consider additional funds for things like child abuse caseworkers and investigators only after creation of the new Department of Child Welfare and Family Services.

Brewer had asked for more than $80 million in new funds for the agency, though Wilder said the governor is willing to accept less for now.

But he said the governor wants to be sure the new agency has the money it needs when it starts up, and not have to come hat-in-hand to the Legislature for what it needs. Wilder said Brewer wants these issues resolved before the budget hits her desk.

“Left unaddressed, it raises doubt whether or not it will ultimately be signed by the governor,’’ he said.

Brewer, who unveiled her own spending plan in January, also is clearly getting annoyed with the Legislature over the budget: Late Tuesday, she threatened to veto anything else sent to her in the interim.

The issue of university funding took center stage Tuesday as the Senate trimmed some of the extra cash the House had agreed to provide, which was already less than Brewer had sought.

In January the governor asked for $27.5 million, but only for Arizona State University and Northern Arizona University to bring their per-student aid up to parity with the University of Arizona.

That got trimmed in the House to $5.5 million. And lawmakers opted to divide that up, with $2.5 million each for UA and ASU, with the balance for NAU.

The Senate budget adopted Tuesday cut that in half, angering Sen. Steve Pierce, R-Prescott.

He said the only reason the state has $5.5 million to spread around is because UA refinanced some of its debt. He said UA, having saved the money, should benefit.

Pierce pointed out that the Board of Regents requested $15 million for UA to add researchers and facilities.

“We gave them zero,’’ he said, even after the UA debt refinancing savings.

Sen. Steve Farley, D-Tucson, agreed the school is being shortchanged.

“The University of Arizona did what was right,’’ he said. “They figured out a way to save money.’’

Some of that is now being spread among the other schools. And some of that, Farley said, is being put into the state treasury.

“What incentive is there for our state institutions, then, to save money if when they save money it gets taken away from them?’’ he asked. “Why would they work so hard to save so much money if they are not going to be able to put it to good use and it’s just going to get into our great slush fund up here?’’

Farley had no better luck in convincing the Republican-controlled Senate to give UA that $15 million for research scientists and facilities.

One of Brewer’s higher education funding priorities did survive: Both the House and Senate budgets have $3.5 million she is seeking for UA’s cooperative extension service, which aids agricultural interests.

Funding for universities, charter schools and the wording of a promise of more dollars for child welfare are not the only issues standing in the way of a new state budget.

House Speaker Andy Tobin said there is strong sentiment among members of his chamber for the state to provide things like emergency dental care and podiatry services. He said the amount of cash involved is small but will save money in the long run as patients get care before they wind up in hospital emergency rooms.