Why are so many conservative Republicans upset about the inevitable nomination of Sen. John McCain, and what are we going to do about it?

The cause of conservative discontent isn't hard to fathom. Start with the Arizona senator's voting record on many key issues. He has opposed pro-growth tax cuts and supported limits on political speech. He has pushed amnesty when it came to illegal immigration and half-measures when it came to interrogating terrorists. He wants to close Guantanamo and allow the reimportation of prescription drugs into the United States. Not only does he part company with conservatives on these and other issues - climate change, drilling for oil in the Alaskan hinterland, federal funding of embryonic stem-cell research, international criminal courts, gun-show background checks - he invariably adopts the rhetoric of the left and stridently leads the opposition.

Set all this against the issues on which he's led conservatives over his three decades in the Senate - opposition to pork-barrel spending and support of the Iraq War - and you can sense why conservatives worry about where McCain's passions lie.

Of course, this wouldn't be the first time Republicans nominated a moderate to carry their banner in November. In fact, from the Great Depression until 1980, Republican presidential candidates were almost exclusively moderates. So why is the prospect of one more Republican moderate atop the ticket causing many conservatives to talk about forming a third party or voting for Hillary Clinton, for goodness' sake?

Because the Republican Party is not the party it was into the 1970s, and neither is the Democratic Party, in spades.

The Republican Party was founded as the antislavery party. It was, thus, a regional party. After the Civil War, the North and Upper Midwest were Republican, the South and Southwest Democratic. With the exception of the solidly Democratic Catholic vote in the Northeast, the North was virtually a one-party region right up to the Great Depression.

I remember walking through the state Senate chamber in Harrisburg and seeing the pictures of the 50 state senators who served at the turn of the last century. It was astounding; 49 of them were Republican.

Were Pennsylvania and the other Republican states in the Northeast "conservative" states? No, they were all mixed bags ideologically. Ideological disagreements rarely split along partisan lines as they do today, because each party had robust "conservative" and "liberal" wings. In Washington, conservatives and liberals were divided on issues, but it was actually easier to find common ground because partisanship didn't work to exacerbate ideological divisions.

All that changed after the 1960s. The Democratic Party embraced the '60s Cultural Revolution, with its hostility to the military and traditional values. The GOP pursued Richard Nixon's Southern Strategy to court Southern conservatives away from the Democratic Party. The Democratic Party became the party of George McGovern and Ted Kennedy. After some stiff resistance, the Republican Party became the party of Ronald Reagan. The upshot today: If you are a conservative, you are a Republican; if you're a liberal, you're a Democrat.

The divide intensified due to the dramatic leftward shift of the Democratic Party. It has morphed into a made-in-the-USA Western European liberal party that seeks to grow the power of government, increase the public's reliance on Washington, wage class warfare, downplay national-security threats, relinquish our sovereignty, redefine the family, and substitute secular humanism for our society's Judeo-Christian underpinnings. As mainstream Democrats, both Clinton and Barack Obama see America as deeply flawed and needing massive "change."

Which brings us back to McCain.

Conservatives understand just how consequential the 2008 election will be. It could very well result in the election of a Democratic president who's prepared to reshape America culturally and economically and unprepared to defend the nation against our foreign enemies. Yet we see a presumptive Republican nominee who has too often joined the very people who seek to destroy and replace what we fight to conserve and improve. And so we wonder: Is this the man we can trust to take our case to the American people?

Many of us want a leader who believes in his core that this race is a fight for the soul of America, her Judeo-Christian tradition, her sovereignty, her courage to defeat not appease or surrender to her enemies, her belief in capitalism and limited government, and her commitment to equality of opportunity, not result. We want a leader who's not interested in moving the country in the same direction as Clinton and Obama, only slower.

Is McCain that leader? It's a question that both he and conservatives will have to answer. My own doubts prompted me to oppose him and, finally, endorse Mitt Romney in the GOP primary. But general elections pose such questions in a different, more complex context, and the best answers come after a period of post-primary decompression.

McCain's predecessor in the Senate, Barry Goldwater, wrote in the opening of

The Conscience of a Conservative:

"The ancient and tested truths that guided our Republic through its early days will do equally well for us. The challenge to conservatives today is quite simply to demonstrate the bearing of a proven philosophy on the problems of our own time."

Will John McCain now embrace those truths and that challenge?