PHOENIX — A federal judge said Thursday he may let the state’s new employer sanctions law take effect while he debates its legality.

 Neil Wake agreed to schedule a hearing Tuesday on the request by challengers to block enforcement of the law set to take effect Jan. 1. They need the restraining order because it is virtually impossible for Wake to have a full-blown hearing on the legal merits of the statute before then, much less issue a ruling.

 The judge said, though, that situation is no one’s fault but the business groups who want the law overturned. Attorney David Selden said if Wake balks, it will have major financial implications for the businesses he represents.

 He noted that part of the law requires all firms to sign up with the E-Verify program. That means having the necessary computer equipment and training employees to use it. Selden said that could run $150 million — $1,000 for each of the 150,000 Arizona businesses affected — money he said would be wasted if he eventually gets a court to conclude the statute is unconstitutional. “It’s not in anybody’s interest to have the law go into effect before there’s a ruling,’’ he said.

 But Wake pointed out these groups and their lawyers were warned by the Attorney General’s Office in September that they may have sued the wrong parties. At that time, state Solicitor General Mary O’Grady said the proper defendants are the state’s 15 county attorneys, the people actually charged with enforcing the law.

 But the business lawyers chose to ignore that warning in challenging the law which allows a judge to suspend or revoke any state licenses of any firm found guilty of knowingly hiring undocumented workers. Wake said that flaw in the legal papers was one reason he threw out their original lawsuit earlier this month.

 The business groups filed new legal papers this week — this time suing the county attorneys — while at the same time asking Wake to keep the law from taking effect while he weighs the issue. “The urgency that plaintiffs feel is of their own making,’’ the judge responded Thursday. He said the business groups “have now dissipated the time available for the appropriate defendants to present their case and for the court to deliberate and rule after hearing both sides.’’

 Selden said he didn’t sue the 15 county attorneys because he didn’t think it was necessary. But he also said there was a “strategic decision’’ to keep the case simple and more efficient.

 But Wake said if a “tactical decision’’ by lawyers of how to pursue litigation results in a delay, that decision “evidences a lack of diligence and is grounds for denial’’ of a restraining order.

 Selden said the county attorneys may want to support his request for the restraining order.

 He said counties — unlike the state — are not immune to lawsuits in federal court seeking financial damages. And Selden said businesses could seek to recover that $150 million in costs if the law eventually is voided.

 The battle over whether to stay enforcement of the law comes as another group of plaintiffs involved in the original cause also filed their own new lawsuit asking Wake to void the law — and their own request for a temporary restraining order.

 Attorneys representing Valle del Sol, Chicanos Por La Causa and Somos America presented their own arguments about why they believe the law is illegal.

But their contentions center not on the harm to companies who are being forced to comply with the law but on arguments that employers, who fear being punished under the new law, will be less likely to hire minorities and foreign born workers — individuals to whom they provide services — who actually are legally entitled to work in this country.