In my 25 years in politics, I’ve never seen an issue as explosive or divisive as immigration reform.

The politics are not conventional; they make for strange bedfellows. This is an issue where Barack Obama and George W. Bush and Jeb Bush are in agreement calling for compassion and pathways to citizenship, while ultraliberal MSNBC host Ed Schultz and right-wing former congressman and Arizona Senate candidate J.D. Hayworth are in agreement about militarizing the border.

About a decade ago, discussion about immigration reform was focused on making U.S law friendlier, or at the very least, reasonable for Mexican immigrants. And the message was carried by unlikely champions such as George W. Bush, who as governor of Texas saw up close the strong work ethic, deep patriotism, strong faith, and enormous contribution Mexican immigrants make to our country. It was that kind of compassionate conservatism that drew independents and Democrats like me to support Gov. Bush.

Advisers counseled Bush to stay away from immigration reform, worried that he would be viewed as too soft and immigrant-friendly. Bush ignored the advice.

I remember during the 2000 presidential campaign when some in the GOP counseled President Bush to stay away from immigration reform, worried that he would be viewed as too soft and immigrant-friendly on the subject, creating a political liability. Bush ignored the advice. And not long after he was elected, he pushed the issue to the front burner of his agenda.

• Bryan Curtis: What Immigrant Crisis?• Benjamin Sarlin: The Latino Backlash Begins• Tunku Varadarajan: Say ‘Hell No’ to ArizonaIf not for the attacks of 9/11, immigration reform would very likely have passed in late 2001 or 2002. President Bush and President Vicente Fox of Mexico were working very closely on the issue until that horrible event reshaped American policy on so many fronts, including immigration.

From then on, things deteriorated steadily. John McCain’s presidential primary campaign melted down in the spring of 2007 because he was viewed as not being punitive enough on immigration reform. Meanwhile, politicians like Tom Tancredo led an ugly race to the bottom to see who could be most xenophobic. And consequently, nothing got done.

Because of the failure at the federal level to enact meaningful reform, our political structure has created the conditions that encouraged and allowed Arizona to pass an ugly, onerous, and, one hopes, unconstitutional law.

And here’s the unfortunate irony. The Arizona situation is likely to compel the Obama administration to push immigration reform up on its agenda. But the worst possible time to discuss or pass meaningful, reasonable, responsible immigration reform is during an election year. The debate and outcome will be dominated by the extreme fringes. The administration would be better off having the Justice Department and courts deal with constitutional issues of the law for now and come back and craft comprehensive legislation after the elections.

In roughly 10 years, we’ve moved as a nation from a political environment that fostered an immigration-reform message that said, “We welcome you with open arms” to one today that says, “We don’t want you here.”

It’s a sad state of affairs and one at odds with the fundamental values that created America and made this country great.

As vice chairman of Public Strategies and president of Maverick Media, Mark McKinnon has helped meet strategic challenges for candidates, corporations and causes, including George W. Bush, John McCain, Governor Ann Richards, Charlie Wilson, Lance Armstrong, and Bono.