Before Republicans put Newt Gingrich at the top of their party, they should consider what happened the last time he led it.

In the mid-1990s, Gingrich was the de facto head of the Republican Party. He helped lead it to victory in the congressional elections of 1994, which brought about real accomplishments such as welfare reform. But once he attained power, both his popularity and that of his party started to plummet. In the aftermath of his leadership, a Republican was able to take the presidency only by pointedly distancing himself from Gingrich.

Conservatives who dislike George W. Bush’s compassionate conservatism have Gingrich to thank for it. After Gingrich lost the budget battles with President Bill Clinton, it took 15 years for any politician to take up the cause of limited-government conservatism that he had discredited.

Although Gingrich isn’t solely responsible for the Republican policy defeats of those years, his erratic behavior, lack of discipline and self-absorption had a lot to do with them. He explained that one reason the federal government shut down in 1995 was that he was angry that Clinton had snubbed him during an international flight. The Clinton White House then released pictures of the two men gabbing on the plane. Later negotiations didn’t go well, with Gingrich saying, “I melt when I’m around him.”

Erratic, Undisciplined, Grandiose

Gingrich’s fans say that he isn’t the same man he was then; he has “matured” in his 60s. Maybe so. But he’s still erratic: This year he flip-flopped three times on the top issue of the day, the House Republican plan to reform Medicare. He’s still undisciplined: He went on a vacation cruise at the start of his campaign. He still has the same old grandiosity: In recent weeks he has compared himself to Ronald Reagan and Margaret Thatcher and said confidently that the nomination was his.

He still has the same need to justify his every petty move by reference to some grand theory. Plenty of politicians competing in Iowa come out for ethanol subsidies; only Gingrich would proclaim that in doing so he was standing up to city slickers in a culture war invented in his own mind. He still has a casual relationship with the truth. In recent weeks he has said that Freddie Mac paid him to condemn its business model, only for reporters and bloggers to find out that he had in fact shilled for the organization in return for about $1.6 million.

He still has the same penchant for sharing whatever revelation has just struck him, as with his recent musings about getting rid of child-labor laws. “He goes off the deep end and throws things out there,” says Joe McQuaid, the publisher of the Manchester Union Leader, which has endorsed Gingrich. He means it as a compliment, but it doesn’t strike me as one of the top traits to seek in a president. Many voters may have the same reaction.

The race for the Republican nomination appears to have come down to two intelligent, knowledgeable men in Gingrich and former Massachusetts Governor Mitt Romney. Neither of them has a history of down-the-line conservatism. Gingrich can match Romney flip-flop for flip-flop and heresy for heresy. He has supported cap-and-trade legislation, federal funding for embryonic stem-cell research, the expansion of Medicare to cover prescription drugs and a federal requirement for everyone to buy health insurance. He has been neither more consistent nor more conservative than Romney.

True, Gingrich has done more to advance the cause of conservatism than Romney. But he’s also done more to damage it. He lost his job as speaker of the House because conservative representatives were fed up with his inconstancy.

A Riskier Choice

There’s no guarantee that any Republican will win next year, of course. But Gingrich would be a riskier choice for the Republicans to nominate against President Barack Obama. The last time the country got a good long look at him, he turned very unpopular very fast. His decades in Washington, some of them spent essentially as a lobbyist, would muddle the party’s message. So would his unfortunate marital history.

We already know the basic strategy of the Obama campaign. It will be to portray the Republican nominee as a dangerous right-wing extremist. Romney’s demeanor -- his steadiness, his reasonableness -- would undercut that strategy. It seems likely to be much more successful against Gingrich. After all, it already was: In 1996, Clinton ran against Gingrich as much as he ran against his nominal opponent, Bob Dole. Clinton portrayed Gingrich as callous and radical, and used Gingrich’s ill-considered words, such as his claim that Republican plans would cause the Medicare bureaucracy to “wither on the vine,” against him.

Gingrich’s energy and creativity are admirable, within limits. But recognizing his own limits is not a Gingrich specialty. Voters are likely to see, as he cannot, that he is temperamentally unsuited for the presidency.

(Ramesh Ponnuru is a Bloomberg View columnist and a senior editor at National Review. The opinions expressed are his own.)

To contact the writer of this article: Ramesh Ponnuru at rponnuru@bloomberg.net.

To contact the editor responsible for this article: Timothy Lavin at tlavin1@bloomberg.net.