There has been lots of talk that Paul Ryan’s nomination ensures that we’ll now have a “real” debate about the role of government. That’s actually funny. The bar for this campaign is so low that we celebrate the fact that it might include a serious debate about one of the four great issues of the day, though even that is not clear yet. And even if Ryan’s entry does spark a meaningful debate about one of the great issues facing America — the nexus of debt, taxes and entitlements — there is little sign that we’ll seriously debate our other three major challenges: how to generate growth and upgrade the skills of every American in an age when the merger of globalization and the information technology revolution means every good job requires more education; how to meet our energy and climate challenges; and how to create an immigration policy that will treat those who are here illegally humanely, while opening America to the world’s most talented immigrants, whom we need to remain the world’s most innovative economy.

But what’s even more troubling is that we need more than debates. That’s all we’ve been having. We need deals on all four issues as soon as this election is over, and I just don’t see that happening unless “conservatives” retake the Republican Party from the “radicals” — that is, the Tea Party base. America today desperately needs a serious, thoughtful, credible 21st-century “conservative” opposition to President Obama, and we don’t have that, even though the voices are out there.

Imagine if the G.O.P.’s position on debt was set by Senator Tom Coburn, the Oklahoma Republican who has challenged the no-tax lunacy of Grover Norquist and served on the Simpson-Bowles commission and voted for its final plan (unlike Ryan). That plan included both increased tax revenues and spending cuts as the only way to fix our long-term fiscal imbalances. Give me a Republican Party that says we have to put real tax revenues and spending cuts on the table to solve this problem, and you’ll get a deal with Obama, who has already offered both, although not at the scale we need. True conservatives know that both Ronald Reagan and George H.W. Bush used both tax revenue and spending cuts to fix budget shortfalls. Ryan-led G.O.P. radicals say “no new taxes,” find all the savings through spending cuts. That’s never going to happen — and shouldn’t.

Imagine if the G.O.P.’s position on immigration followed the lead of Mayor Michael Bloomberg and Rupert Murdoch, chief executive of the News Corporation. Bloomberg and Murdoch recently took to the road to make the economic case for immigration reform. “I think we are in a crisis in this country,” The Times quoted the Australian-born Murdoch, who’s now a naturalized American, as saying last week. “Right now, if we get qualified people in, there shouldn’t be any nonsense about it.” Regarding the “so-called illegal Mexicans,” Murdoch added, “give them a path to citizenship. They pay taxes; they are hard-working people. Why Mitt Romney doesn’t do it, I have no idea, because they are natural Republicans.”

Imagine if the G.O.P. position on energy and climate was set by Bob Inglis, a former South Carolina Republican congressman (who was defeated by the Tea Party in 2010). He now runs George Mason University’s Energy and Enterprise Initiative, which is based on the notion that climate change is real, and that the best way to deal with it and our broader energy challenge is with conservative “market-based solutions” that say to the fossil fuel and wind, solar and nuclear industries: “Be accountable for all of your costs,” including the carbon and pollution you put in the air, and then we’ll “let the markets work” and see who wins.

Imagine if G.O.P. education policy was set by former Gov. Jeb Bush of Florida, without having to cater to radicals, who call for eliminating the Department of Education and view common core standards as some kind of communist conspiracy. Mr. Bush has argued that a conservative approach to education for 21st-century jobs would embrace more effective teacher evaluation and common core standards, but add a bigger element of choice in the form of charter schools and vouchers, the removal of union rules that limit new technology — and combine it all with greater autonomy and accountability for individual principals. When parents can choose and school leaders can innovate, good things happen.

We are not going to make any progress on our biggest problems without a compromise between the center-right and center-left. But, for that, we need the center-right conservatives, not the radicals, to be running the G.O.P., as well as the center-left in the Democratic Party. Over the course of his presidency, Obama has proposed center-left solutions to all four of these challenges. I wish he had pushed some in a bigger, consistent, more daring and more forceful manner — and made them the centerpiece of his campaign. Nevertheless, if the G.O.P. were in a different place, either a second-term Obama or a first-term Romney would have a real chance at making progress on all four. As things stand now, though, there is little hope this campaign will give the winner any basis for governing. Too bad — a presidential campaign is a terrible thing to waste.