MADISON, Wis. – Why, during a recent visit here – while asking some trusted Wisconsin sources for their candid assessment of Scott Walker, the state’s governor, an undeclared but leading 2016 Republican presidential candidate – did I keep thinking about a conversation I’d had 17 years ago with one of my favorite American politicians and the most recent Democrat to win the Texas governorship, the late Ann Richards?

You see, Richards used to remind audiences she was only the second female governor of Texas, that the first had been Miriam Amanda “Ma” Ferguson, who had followed her impeached husband, “Pa” (honest) Ferguson.

The big issue of Ma Ferguson’s governorship was a heated public debate over whether to teach foreign languages in Texas’ public schools.

Ma Ferguson came out against the teaching of foreign languages with, Gov. Richards insisted, this statement: “If the English language was good enough for Jesus Christ, it’s good enough for the schoolchildren of Texas.”

At a small dinner in 1998, I asked Richards what we should know about George W. Bush, the man who had defeated her four years earlier and was then preparing to run for the White House. She answered emphatically: “George W. Bush should not be underestimated.”

In private conversations, Wisconsin wise-hands seemed to echo Richards. Only this time it was “Scott Walker should not be underestimated.”

Think about it. In every one of the past seven presidential elections, beginning with Michael Dukakis in 1988 and including 2012 (by a decisive margin over the GOP ticket, which included native son Rep. Paul Ryan), Wisconsin has voted Democratic. This is the state that only three years ago elected the first openly lesbian U.S. senator, Democrat Tammy Baldwin, in U.S. history.

Yet Republican Scott Walker, after winning two terms as Milwaukee County executive and while running and operating as an unapologetic conservative, won the governorship in 2010 and became the first American governor ever to defeat a recall effort, in a 2012 election. He was re-elected last year. Three statewide victories in four years.

For Republicans who have unsuccessfully battled the GOP’s negative stereotype as the party of the privileged and the well-off (remember Mitt Romney’s Cayman Islands accounts and the “47 percent”?), Walker – the son of an unprosperous Baptist preacher – who has regularly made and carried his own lunch from home, personifies the walking rebuttal to the country-club conservative image.

He made himself a hero to conservative activists and major conservative donors when he took on and crippled public employee unions in the state where they were created, stripping them of their collective bargaining rights and effectively dismantling the union movement.

Republicans who are forever looking for another Ronald Reagan have not found him in Walker, whose campaigns are not about convincing voters on the other side of the political divide – as the Gipper was able to do by welcoming “Reagan Democrats” to his cause – but instead concentrate all their attention on organizing and turning out the already converted. Compare Reagan’s average margin of victory – an impressive 13 percent – with Walker’s 5 percent.

A new poll by the widely respected Marquette University Law School shows that Walker’s Wisconsin approval rating has fallen to 41 percent, with 56 percent of voters rating him unfavorably.

This represents a 17-point drop since November.

Though Walker leads his would-be closest Republican presidential challenger in Wisconsin – Sen. Rand Paul of Kentucky – by 30 points, the Marquette survey shows him now trailing Democrat Hillary Clinton 52-40 percent.

But if Ann Richards were still here, I think she would be warning her fellow Democrats: “Do not underestimate Scott Walker.”

Editor’s note: To find out more about Mark Shields and read his past columns, visit the Creators Syndicate website at www.creators.com.