The question is whether voters in future primaries decide the race is effectively over after Tuesday and flock to Romney, or whether Santorum lives to fight another day in the polls. A big-enough night for Santorum could prolong his eventual defeat, since polls tend to be more short-sighted than markets. Here are the odds for tomorrow's individual elections:
We can predict with near certainty that Romney will win in Virginia (where only he and Ron Paul are on the ballot), his home turf of Massachusetts, neighboring Vermont, and Idaho. Gingrich likewise has odds of about 95 percent in Georgia.
Romney has 81.6 percent odds in the crown jewel, Ohio, though polls—which lag compared to markets—have him virtually tied with Santorum. (The odds swung significantly in his favor after last week's wins in Arizona and Michigan.) As we've noted before, this literally means that 1 out of 5 times, Santorum pulls off an upset win. Meanwhile, Santorum has 88.6 percent odds in conservative Oklahoma.
That leaves North Dakota and Alaska, where Romney has odds around 75 percent, and Tennessee, where Santorum leads with 57 percent of the vote.
There are 419 delegates at stake Tuesday, and Romney could take the vast majority if he meets or exceeds expectations. The former Massachusetts governor already has an 86.4 percent chance to be the Republican nominee for president, and he will still be the overwhelming favorite to win the nomination regardless of the outcome on Super Tuesday. The question is whether he can effectively seal the deal Tuesday, or leave Santorum enough delegates to hang on to even an imaginary claim to the nomination.
David Rothschild is an economist at Yahoo! Research. He has a Ph.D. in applied economics from the Wharton School of Business at the University of Pennsylvania. Follow him on Twitter @DavMicRot and email him at thesignal@yahoo-inc.com.
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Mitt Romney speaks during a town hall meeting campaign stop at Eagle Manufacturing Corporation February 21, 2012 in Shelby Township, Michigan.Romney’s earlier economic plan called only for preserving the current top tax rate of 35 percent, while holding out the promise of lower rates later in an overhaul of the tax code. 
Santorum and former House Speaker Newt Gingrich, who has proposed an optional “flat tax” system of 15 percent, have accused Romney of timidity. With his new proposal, Romney seeks to counter that charge in advance of the Arizona debate. Romney’s plan aims to balance two competing priorities of different Republican factions. By proposing to cut the top rate, he bids for support among supply-side conservatives who contend that lower marginal rates are the key ingredient for producing economic growth. But by vowing to offset the loss of revenue by eliminating some deductions, he responds to concerns among deficit hawks about expanding the tide of red ink that has the federal government spending an estimated $1.3-trillion more than it takes in this year. And by insisting that those unspecified reductions will fall most heavily on the affluent, he seeks to limit his own exposure as a wealthy former financial industry executive who himself has paid taxes at only around the 15 percent rate because most of his income comes from capital gains. Romney would maintain the current 15 percent rate on dividends and capital gains. Obama has proposed to tax the “carried interest” received by many hedge fund ![[cnbc explains]](/CNBCexplainsicon1.gif){kind=small}
and private equity executives at higher ordinary income rates rather than as capital gains, arguing that current law gives them an undue advantage. Hubbard said a President Romney would ask his treasury secretary to study the “devilishly hard question” of whether current law should change and tax some of that income at ordinary income rates. Romney had previously proposed eliminating capital gains taxes on taxpayers earning less than $200,000. That drew fire from some conservatives, and campaign rivals such as Gingrich, on grounds that gave unwarranted preference to a specific group and would have a small economic impact since those taxpayers receive relatively little in capital gains anyway. Romney also proposes to eliminate the estate tax and the Alternative Minimum Tax, while cutting the top corporate tax rate from 35 to 25 percent. Hubbard said three different revenue streams would keep the plan from increasing the budget deficit: the “dynamic” effects of economic growth, the additional income that would be subject to taxation through “base broadening," and spending cuts Romney plans that would reach $500 billion per year by 2016. The campaign promised more specifics on those spending cuts within the next week. In advance of Romney’s tax plan, Obama’s Treasury Department proposed its own corporate tax overhaul plan cutting the top corporate rate to 28 percent by eliminating some existing corporate deductions. Part of the Obama plan includes a minimum tax on the overseas income of U.S.-based corporations.