Republican presidential hopeful John B. Connally today stepped up his attack on Ronald Reagan, suggesting the former California governor may have neither the mental nor physical capacity to be president.

At various points during a day of campaigning, Connally raised questions about the 68-year-old Reagan's ability to endure a strenuous campaign, and suggested that Reagan is a "cue-card candidate."

Connally also charged Reagan, who was endorsed last Saturday by the Iowa Pro-life Political Action Council, an anti-abortion group, with signing into California state law a 1967 bill that liberalized abortions.

The former Texas governor also predicted, for the first time, that George Bush, the former CIA director and U.N. ambassador, would defeat Reagan in the Jan. 21 Iowa precinct caucuses, the first formal test of the 1980 presidential campaign.

Connally, who conceded he has little hope of coming in first or second in the Iowa caucuses, resumed his campaign in Iowa for the first time since the Republican presidential debate last Saturday in Des Moines. Reagan refused to appear in the debate, saying he thought such forums were divisive.

Complaining that Reagan "always wants to accuse others of being divisive," Connally said in an interview, "If it were not for his challenge [for the 1976 Republican nomination], Gerald Ford would still be president."

Connally, who made appearances today here and in Council Bluffs, told reporters, "We really haven't said anything yet. The campaign has just started. The campaign is going to be far more interesting in the future than it has been in the past."

Connally began making barbed remarks about Reagan early in the day when he learned that Reagan had suggested last Monday that Connally "must have been living under a rock" for not knowing Reagan's campaign positions. This was a reference to a statement Connally made during Saturday night's debate.

"I think we're finally getting under his skin," Connally said as he huddled against a chill eight-degree wind at the airport runway in Council Bluffs.

Reagan, he said, has been able to sustain a huge lead in the public opinion polls "by his inaction."

Ninety minutes later, he told a news conference in Cedar Rapids, "I suppose the reason I don't know much about his [Reagan's] positions is you can't get much on a three-by-five card."

This was a barbed reference to the small, white cards that Reagan has used for decades to make speech notes.

Connally's attacks come at a time when his well-financed and highly publicized campaign is trying desperately to regain the momentum it lost last fall when Reagan defeated him in a straw poll at a Florida Republican Party convention.

"No one," Connally warned, "should approach the nomination thinking they have it all wrapped up or deserve it, or that it is to be a trophy awarded to the one [candidate] who has delivered enjoyable one-liners over the longest period of time."

And in a thinly veiled reference to Reagan's age, Connally said:

"I think everyone knows the presidency is the most demanding job in the country, requiring mental agility, physical stamina and endurance. I think every candidate has the burden of satisfying the American people that he can withstand the rigors of that office."

On the abortion issue, Connally charged that Reagan signed a bill liberalizing California abortion laws in 1967, the same year Connally successfully fought such legislation in Texas. Connally said that about 750,000 additional abortions were performed under the law between June 1967 and when Reagan left office in 1973, and he suggested that Reagan's current anti-abortion stance is one he has "lately come to."