They will warm up in early July with an already controversial plan for ``random'' bag searches, T police Chief Joseph Carter said, citing post-Madrid bombing concerns about terrorist attacks on mass transit.

"What we're looking at with the DNC is that we'll ask the public not to bring bags,'' Carter said. ``There will be people who obviously can't live to that standard. They'll have to understand their bags will be subject to inspection."

He acknowledged that could mean lines at T entrances. But he said he hopes people will avoid commuting that week.

Carter said officers will be trained to conduct random searches without profiling, while singling out anyone acting suspiciously. But the T's effort to develop a bag-check policy already is drawing fire.

MBTA cop union President Robert Powers said he is concerned random checks will mean lawsuits.

"The only way we can search is with probable cause," Powers said. He added he doubts all bags on the T can be checked: "We have a million people a day with backpacks, briefcases and lunch bags. Are we going to check all of them?"

Carol Rose of the American Civil Liberties Union called random checks a "false security measure," saying they can miss actual terrorists. She said ACLU callers have complained random checks would make a T ride "too much like the former Soviet Union.'' Checking all bags might circumvent profiling concerns, she said.

T riders indicated they aren't crazy about the idea, either.

"I think they shouldn't have the Democratic National Convention,'' said Hemant Shah of Malden. ``I have mixed feelings about it."

"I think it's ridiculous because it will hold people up," said Erika Ramos of Dorchester, but she added, "With everything going on, if it's necessary, it's OK."

Wendy Bugden of Quincy agreed: "If it will make things safer, then I don't mind."