Washington ? When George Romney was the Republican governor of Michigan 40 years ago, his lieutenant governor was William Milliken, the personable heir to a department store dynasty in Traverse City.

They were partners in a socially progressive, business-oriented state administration, notable for its involvement with the economic struggles of heavily Democratic Detroit.

When George Romney challenged Richard Nixon for the GOP presidential nomination in 1968, Milliken and his wife, Helen, gave Romney their full support. And when Romney left the governorship the next year to become Nixon’s secretary of housing and urban development, Milliken became his successor. He won election three times – serving for a record 14 years as a popular chief executive until he retired in 1983.

When I reached Milliken by phone at his home five days before Tuesday’s Michigan primary, I asked whether he was involved in the current GOP campaign. “I haven’t been,” he said, “but I’m about to jump in. I’m waiting for a phone call from John McCain so I can tell him I’m endorsing him.”

Milliken’s decision is not a surprise. He did the same thing eight years ago, when McCain followed up his victory over George W. Bush in New Hampshire by winning Michigan – the last significant state the Arizona senator won before the battle turned against him.

Nonetheless, for anyone with a sense of history, Mitt Romney’s inability to persuade his father’s closest political ally to join him in what has become his own last stand is a poignant moment.

Though Mitt Romney chose Massachusetts, his business headquarters, as the place to root his political ambitions, running first for the Senate and then being elected governor, it is Michigan that has been his favorite venue. He announced his candidacy for president at the Henry Ford Museum in Dearborn and has long believed that he has a personal base in the state where he spent his boyhood years.

Milliken told me that his decision to go with McCain once again was primarily a reflection of personal admiration. “Though I don’t agree with him on a couple issues, he is so honest and straightforward,” he said. “I just respect his integrity.”

On immigration, Milliken said, McCain “has been steadfast, even though his legislation was unsuccessful. He has resisted the effort to demagogue the issue. I like him for that. He’s been very good on the environment and global warming. He’s taken a position on Iraq that I don’t happen to agree with, but he’s been straightforward and steadfast.

“There is an overall sense of integrity superior to everyone else in the field, even at the risk of taking positions that are not politically popular.”

Bill and Helen Milliken are known in Michigan as advocates both of civil rights and abortion rights – the latter being another issue on which they differ from McCain, who has always opposed abortion. These policy differences could be decisive, but the character traits clearly loom larger.

When I asked Milliken about Mitt Romney, he said he had not known him well before this year. “He was quite a young fellow when his dad and I served together, and he left Michigan as a youth. But I met with him at his request a couple months ago when he was here campaigning.”

What did you think? “He has switched positions quite regularly,” Milliken replied. “He has become much more conservative than his father ever was. I doubt his father would approve his hard swing to the right.”

Mitt Romney, who idolizes his father, would certainly disagree with that assessment. And his campaign was quick to note that Milliken has deviated so far from Republican orthodoxy that he endorsed John Kerry for president in 2004 over Bush.

At the time, Milliken noted that he had worked tirelessly to help the elder George Bush carry Michigan against Ronald Reagan in the 1980 primary. But he criticized the current president for “pandering to the extreme right wing” and for having “rushed us into a tragic and unnecessary war that has … alienated this nation from much of the world.”

Milliken is in some respects a throwback to a vanished generation of Republican moderates. But he is hardly alone in wondering about the many shifts in policies and tactics that have marked this Romney campaign.

It is somehow fitting that in Michigan – with Milliken – the pattern may finally cripple Romney’s candidacy.