The not-Romney Republican candidates for president keep imploding.

From Michele Bachmann to Newt Gingrich, a string of presidential hopefuls have held the lead in the race, only to fade as another flavor-of-the-month surges to the lead. After Romney victories in Iowa and New Hampshire, the string is running out. Ron Paul’s loyal following has been steady, but not enough to grab the nomination.

The endorsement of Rick Santorum over the weekend in Texas by 150 evangelical Christian leaders is a last-ditch effort to stop Romney in South Carolina.

A Reuters/Ipsos poll of likely South Carolina Republican voters pegs Romney at 37 percent and Paul and Santorum tied at 16 percent. Gingrich, whose Super PAC continues to attack Romney as a “corporate raider” while the candidate asks the PAC to “correct errors” in the ads, is fourth at 12 percent. Perry has 6 percent.

A Romney win in South Carolina would propel him to unstoppable momentum, especially if his current lead holds in Florida, the next-in-line primary state.

Can Santorum stop Romney in South Carolina? Is Santorum the conservative alternative to the “Massachusetts moderate”?

No and No.

First, Santorum has few relevant credentials, low Republican voter (remember Arlen Spector?) support and little money.

Politically speaking, Santorum is an ex-U.S. senator who was defeated for re-election in 2008 by an 18 percent margin. Even successful Republican senators make unsuccessful Republican presidential candidates. Ask Goldwater, Dole or McCain. The last successful Republican senator/presidential candidate was Warren Harding.

The successful presidential candidacy of Sen. Barack Obama proves my point.

Members of a legislature do not make good candidates for an executive position, regardless of whether you’re talking about mayor, governor or president. Legislators opine endlessly on what ought to be done without fear of the consequences, without having to live with or administer the laws they pass. Like professors, legislators tend to prattle on regarding any subject, untethered to the real world.

Absent a vice president as candidate, Republican voters favor governors and ex-governors as presidential candidates on the logical ground that governors have actually run the executive branch of a state, dealt with a legislature often dominated by a Democratic majority and have a record on taxes, spending and the rest of the list of political topics.

Republicans (and many other Americans) liked Ike because Eisenhower had proven his executive ability in World War II. He knew how to run a large, unwieldy, government operation and produce victory.

In Manchester, N.H., on Election Day, I joined a round table at Radio Row to question Rick Santorum.

Citing the lack of successful Republican senators/presidential candidates since Harding, I asked Santorum what in his record in the Congress would indicate he knew how to get control of the runaway Obama federal leviathan.

His answer was a confirmation of my worst fears that service in the Senate was not the right experience to prepare for the demands of the presidency.

Santorum first cited his reputation as a reformer and a “bomb thrower,” able to “shake things up.” He bragged that he had “uncovered scandals” and “moved public opinion” on entitlement reform. He compared himself to Lyndon Johnson, who he called the “most effective president in the last 50 years.” Santorum concluded that real change could only come from someone who knew how to get laws passed through the Senate. Hear the whole exchange here:

Others have detailed the pros and cons of Santorum’s legislative history. Holding up the failed presidency of Lyndon Johnson as a model for a Santorum presidency was enough for me.

As to the question of whether Santorum is the conservative alternative to Romney, again the answer is no.

Santorum consistently championed earmarks of federal funds for his favorite recipients in Pennsylvania, bypassing the appropriations process to bestow these favors.

While earmarks do not add up to even a significant portion of the runaway debt problem, the attitude that public money is available to a senator to allocate to favorites outside of the regular budget process is an example of the lawlessness that permeates the federal government and has culminated in Obama’s “We can’t wait” attitude of ignoring Congress and the Constitution.

So why did the social conservatives gathered in Texas unify behind Santorum? Tony Perkins of the Family Research Council said he was looking for a candidate who will fight for pro-family values. In other words, use the power of government to regulate, tax, fund (or defund) programs to advance a social values agenda. Sure it’s big government, but it’s our big government. This is conservative?

At the same time, these 150 folks declined to ask the other “conservative” candidates (Perry and Gingrich) to get out of the race and unite behind Santorum.

In 2008, evangelical voters in South Carolina split their vote between Mike Huckabee and Fred Thompson, allowing John McCain to win and go on to win the nomination. With Perry and Gingrich still in this year, and Paul getting a fair share of the evangelical vote as well, without unity behind Santorum, Romney looks like the beneficiary of the latest stop Romney effort.

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