It seems like an eon ago that John McCain and Sarah Palin came roaring out of the Republican convention with Barack Obama flummoxed by McCain’s vice-presidential choice. That was before the collapse of Lehman Bros. three weeks ago and the deepening of the financial crisis that has wiped everything else from the news.

McCain has seen all the work he did over the summer and with the pick of Palin blown away. He is trailing in the daily tracking polls by about eight points, and his numbers in the battleground states, following the national numbers, have tanked. No wonder McCain is eager to turn the page on this chapter of the campaign, and talk about something else — Obama’s connection to Bill Ayers, for instance.

But the financial crisis and the weak economy aren’t going to disappear as issues. How should McCain address them?

First, he needs to address middle-class concerns. People were worried about the state of the economy before the financial crisis became dire, largely because of the state of their wallets. We have long advocated that McCain adopt a substantial middle-class tax cut, but the hour is late. McCain may have to make do with the policy arsenal he already has. He should do more to publicize his proposal to double the tax exemption for children, which would amount to more than $1,000 for a typical family. Of late, he has wisely been trying to present his entire economic agenda as a way to lower the cost of living. He spoke yesterday in New Mexico of getting “the rising cost of food and gas under control.” He needs to do more, especially with regard to his health-care plan (see this related editorial). McCain’s plan will lead to a large increase in wages as employers convert health benefits into cash for their workers. The result could be a $12,000 increase in take-home pay for a typical family. Obama’s health-care plan, by contrast, is a small-business job-killer.

Second, McCain needs to make the case that his agenda will do more to promote growth. Obama wants higher taxes, including on capital gains. It is hard to think of a worse time to implement that proposal. Obama has been hostile to trade, one of the strongest engines of the economy in recent years and itself a downward force on the cost of living. He has proposed an avalanche of new spending, adding up to almost $1 trillion during his first term. Even Obama has admitted that his tax hikes could hurt the economy; how else to make sense of his comment that he might not impose them if the economy is still faltering? McCain’s tax cuts, spending restraint, and stalwart support for free trade are much better suited to reviving the economy. But McCain has too often overemphasized the spending restraint without putting it into the larger context of an overall economic policy that helps the middle class. He cannot afford to keep making that mistake.

Third, he needs to make a credible pledge not to allow anything like this financial crisis to recur. Fannie Mae and Freddie Mac should lose their privileges. Capital requirements throughout the financial industry should be gradually increased. Clear lines of regulatory authority should be established, consolidating existing bodies where needed.

Fourth, McCain must tie Obama to the liberals in Congress. Congress is as unpopular, if not more so, than President Bush. It had a huge hand in stoking the mortgage mess (see again: Fannie and Freddie). With Democrats sure to get larger majorities in the House and the Senate, they will be emboldened to push Obama’s already liberal agenda leftward off a cliff. And Obama has shown no willingness over the years to stand up to his own party.

This is the deeper political import of his relationship with Bill Ayers and the Rev. Wright. For all his talk about change, Obama has been far better at adapting to the environments in which he finds himself. In Chicago, he had no enemies to the left. He took care not to alienate the city’s corrupt establishment. In Congress, he voted in lockstep with his fellow Democrats. Independence is not his strong suit. If a Democrat wins the presidency, there will be very little check on Nancy Pelosi and Harry Reid — and especially if this weak-willed Democrat wins.

McCain needs to ask whether it would serve the national interest to create the most left-wing Washington in decades. He needs to ask it with respect to many issues, but the economy is certainly one of the top ones. As the economy sinks, do we want more taxes, spending, and trade restrictions? Are Pelosi and Reid, along with a pliable Barack Obama, the people to lead the nation out of this crisis? Is this really the change we want?

The most important reason to hope McCain is elected is that he would keep the country from going on an ideological bender that it does not truly want. That is the case for McCain. He may as well make it.