In an attempt to portray John B. Anderson as a Democrat in Republican clothing, Ronald Reagan said today Anderson should examine his conscience and see whether he belongs in the GOP.

"A party isn't a fraternity" Reagan said. "It isn't something that you join because you like the old scool tie they wear. It is a gathering together of people who basically share the same political philosophy."

Reagan made his comments at a news conference here after a similar statement on ABCs "Issues and Answers."

In the choice days of an Illinois primary widely regarded as a down-to-the-wire race between Reagan and Anderson, the former California governor is trying to rally a solid Republican vote he hopes he will withstand an anticipated Democratic and independent crossover favoring Anderson Tuesday.

Polls taken for Reagan show him with big lead among Republicans and Anderson with an ever heavier margin among the crossovers. The election would seem to hinge on how many crossover voters participate in the Republican primary.

Reagan said he is seeking votes of Democrats who share conservative Republican principles while Anderson attracts "the Kennedy type of Democrat as a crossover vote."

"I don't think they are the kind you could say would be sympathetic to general Republican philosophy," Reagan said on ABC.

Reagan said he is seeking votes of that Anderson should be read out of the Republican Party. But he said the Illinois congressman should try to answer whether he is "more sympathetic with the principles enunciated by the people in the ther party" and whether he is "bucking the tide" in his own party.

". . . If John Anderson believes the things he has said -- his inability to support Republican candidates, his inability to go along with the philosophy that did appear last time and will appear again in the Republican platform -- well then, I think he has to in clear conscience ask if he's in the right place," Reagan said.

Asked for examples of Anderson's deviation from Republican principles, Reagan mentioned Anderson's proposal for a 50-cent-a-gallon gasoline tax and his opposition to the Kemp-Roth tax reduction bill, which Reagan supports.

But the other principal Republican contender in the Illinois primary, George Bush, also is opposed to Kemp-Roth. Regan is trying to ignore Bush, and some Reagan aides believe Bush will take as many GOP votes in Illinois away from their candidate as he does from Anderson.

Reagan expressed gratitude to former president Gerald R. Ford, who said in California Saturday that he would not be a candidate for president. Reagan said he "admired" the decision because it avoided a party split and because he knew that Ford had wanted to run.

Ford's decision not to run is viewed as a plus in the Reagan camp.

"There were some Republicans out there who were holding back to see what Ford would do," said Frederick K. Biebel, Reagan coordinator for state Republican organizations. "With Ford out they're going to come to us."

Reagan received another boost today from a Chicago Tribune poll, taken after Thursday's Republican debate, which showed Reagan with a 36 to 34 percent lead over Anderson. Bush had 12 percent and most other voters were undecided.

Bush, fatigued in recent days, had only two events scheduled today. He flew from Washington to New York to visit eight of the 11 Bush campaign workers taken hostage by Puerto Rican nationalists Saturday.

"They were still very shook up," Bush told a news conference. "I didn't feel right not going and talking to them."

After flying here early this afternoon, Bush issued a statement attacking President Carter's new budget proposals, calling them "too little too late." Bush said he supports Carter's attempt to try to balance the budget, "but these measures should have been taken a year ago, and in absence of action -- any action -- by the president, the crisis has grown worse. He has consistently demonstrated an inability to project events, much less recognize their meaning when they develop."