WASHINGTON — Has America become a mean, ungenerous, cramped and crabby nation, a deeply insecure colossus — one that just might be taking all those Viagra, Apcalis and Cialis commercials a bit too personally? Is the country desperate to find scapegoats to blame for a perceived decline in, um, vigor? Or is America still a confident land of hope and promise, a place still potent with possibility?

It’s watching the Republicans in Congress and on the presidential campaign trail that makes me pose those sweeping questions. I’m just suggesting a context for assessing the actions and rhetoric of a party that seems to be in the throes of andropause.

That’s the popularly accepted term for “male menopause,” which medical dictionaries tend to describe as a “purported” syndrome rather than an actual clinical diagnosis. I’m not qualified to offer an opinion on whether dads go through a Y-chromosome version of what used to be euphemistically called the “change of life.” But I think the “Daddy Party” has been presenting clear symptoms.

The latest was the Senate vote Wednesday in which Republicans, supported by a handful of red-state Democrats, narrowly scuttled the Dream Act, a bill that would have provided a path to U.S. citizenship for some young undocumented immigrants — but only those who did everything this country once found worthy and admirable in pursuit of the American Dream.

Under the proposal, men and women who fulfilled several conditions — they had to be under 30, had to have been brought into the country illegally when they were younger than 16, had to have been in the United States for at least five years and had to be graduates of U.S. high schools — would have been given conditional legal status. If they went on to complete two years of college or two years of military service, they would have been eligible for permanent residency.

Let’s see. Here was a way to encourage a bunch of kids to go to college rather than melt into the shadows as off-the-books day laborers — or maybe even gang members. And here was a way to boost enlistment in our overtaxed armed forces. Aren’t education and global competitiveness supposed to be vital issues? Aren’t we fighting open-ended wars in Iraq and Afghanistan?

The vote against the Dream Act was so irrational, so counterproductive, that it seemed the product of some sort of hormonal imbalance.

“I do not believe we should reward illegal behavior,” sniffed Senate Minority Leader Mitch McConnell, R-Ky., who led the successful fight to kill the measure. But the potential beneficiaries of the Dream Act didn’t do anything illegal; it was their parents who made the decision to come here without papers.

The real reason for denying at least 1 million young people the opportunity to make this nation stronger is that illegal immigration is the scourge du jour. Undocumented immigrants are convenient scapegoats for perceived American decline, convenient targets for the unfocused anger that Republicans seem to believe their constituents feel — the sense that “they,” whoever they might be, are taking something away from “us.”

George W. Bush’s veto of the bill reauthorizing the popular State Children’s Health Insurance Program — an action backed up by loyal House Republicans — had the same defensive, bitter sense of we’ll-show-them-a-thing-or-two. The Republican Party has to be aware of the polls showing how concerned Americans are about the health insurance crisis. They have to be betting that the act of saying no — in what looked like a fit of andropausal pique — would play better with voters, perhaps subliminally.

And just listen to the Republican candidates’ rhetoric about our great nation’s place in the world. With the exception of Ron Paul, every one of them agrees that America is under siege, molested not only by dangerous bands of Islamic terrorists — which is true — but also by sovereign nations such as Iran, China and Russia that have had the temerity to pursue what they see as their own national interests. Which is a bizarre way of looking at foreign relations.

The solution, according to the Republican presidential hopefuls, isn’t give-and-take negotiation. It’s chest-thumping. It’s a series of declarations about what we will find “acceptable” and what we won’t. Maybe this is calculated; maybe they’ve decided that national security is the only issue that gives any of them a chance against any Democrat in 2008.

But I think they’re badly misreading the country. I think this is still fundamentally a hopeful, generous nation, aware of both its challenges and its strengths. And not yet ready to start downing Levitra by the handful.

Eugene Robinson’s e-mail address is eugenerobinson(at)washpost.com.