With presumptive Republican Party presidential nominee Mitt Romney's selection of U.S. Rep. Paul Ryan, R-Wis., as his vice presidential running mate, the very conservative Tea Party faction has become the political party's base, but it's a selection that won't change the outcome of the 2012 election. Here's why:

Putting on the old political science hat for a moment, decades of survey research confirm that the vote for U.S. president is exactly that: Americans, every four years, base their vote on the top of the ticket -- who's running for president -- not who's running for vice president. A voter's attitude toward the candidate (ATC), along with the voter's party identification (PI), and the issue most important to him/her (MSI), are the three factors that determine the vote.  (For those interested in the political science equation, that's: PI + ATC + MSI = Vote.)

To be sure, vice presidential candidates often can deliver their home state, but the overwhelming majority of bottom-of-the-ticket nominees have had little impact on the November vote.

VP Selection: A 'Bump' That Doesn't Last

Now don't be confused by the short-term, usually positive boost in the polls -- which the media calls "a bump" -- that results from the introduction of the vice presidential nominee. This "bump," with a few exceptions, is almost always temporary, and sometimes, as the selection of former Alaska Gov. Sarah Palin as vice presidential running mate for 2008 Republican presidential nominee U.S. Sen. John McCain, R-Ariz., demonstrated, it can reverse and leave a presidential nominee worse off than before the vice presidential introduction. But know that a negative impact is rare, too, hence the most enduring VP selection trend in the modern era is: Beyond his/her home state, usually, the VP choice results in little enduring change in the polls.

Also, don't be confused by instant analysis and superficial observations that note that the choice by Romney of Ryan has "re-energized the campaign," "inspired the party's rank and file," and "added a heavy-hitter to the ticket" etc. Again, see the voter equation above: After party identification, an adult's vote is determined by his/her attitude toward the presidential candidate, and by objective events -- an issue(s) that's most important to the adult. Again, it's highly unlikely that Ryan's selection will change the latter two variables.  

Romney: Still Talking About Everything, Except What Matters Most

Further, Romney's choice represents another mistake by his campaign, or it provides further evidence that the Romney campaign (or national Republican Party leadership) knows very little about voting behavior.

That's because Romney's choice -- if the campaign's debate is restructured so that it conforms to Ryan's Tea Party agenda -- takes the debate away from the one issue that Romney must talk about in order to win: jobs.

Underscoring, the one issue that can boost Romney's standing in the polls -- the one issue that President Barack Obama is vulnerable on -- is: jobs. More than anything else in 2012, the American people want jobs, and by extension, a candidate to demonstrate that he/she has a plan to get the U.S. economy growing at a faster rate and lower the U.S.'s unacceptable, horrible 8.3 percent unemployment rate.

Every day that Romney doesn't talk about jobs is another positive day for the Democratic Party and President Obama. In other words, every day on the campaign Romney should be talking jobs.

Instead, what has dominated the Romney campaign's discourse to-date?

* Romney's failure to release his U.S. income tax reports. (Romney should have released 10 years worth, as soon as the issue surfaced, to resolve the issue.)

* Romney's years at Bain Capital.

* Whether President Obama believes a small business is built entirely by the owner's efforts, or whether public policies (education, infrastructure) and the actions of others (family, friends, teachers) play a role in building the business.

* Romney's commitment to repeal Obamacare, the 2010 U.S. health care reform act.

In sum, Romney to date has spent the bulk of his time talking about everything except the one issue Obama is vulnerable on, the biggest problem the American people want solved, the one issue that can boost Romney in the polls: jobs.

Now, Campaign's Debate Will Shift To The Strengths Of '1912' U.S. Budget

And now, with the selection of Paul Ryan, the discussion will be centered around what? Ryan's controversial, far-right fiscal policies -- including policies that would take the nation back to a so-called better, simpler time -- pre-social welfare state, in Ryan's view -- i.e. to a budget the U.S. government had in, say, 1912. Those ideas include:

* Ryan's plan to end Medicare as we know it: to turn Medicare into a voucher system that will leave many senior citizens about $6,000 to $8,000 short of the annual premium to purchase health insurance in the private sector.

* Ryan's proposed federal budget that calls for even more tax cuts for upper-income groups (including millionaires and billionaires), only partially paid for by cuts in middle-class and working-class programs, and senior citizen and student programs.

* Ryan's plan to cut projected spending for Medicaid, which provides health care for the poor; and his plan to cut food stamp spending -- a program that has literally kept millions of unemployed and lower-income Americans from choosing between buying food or paying other monthly bills.

In short, Romney's selection of Ryan has restructured the debate from "Romney" to "I, Mitt Romney, favor the Tea Party's fiscal program -- spending, taxes, debt and social policies. You see: I have proof: I chose Tea Party poster person Paul Ryan as my running mate."

In other words, it keeps the campaign's debate structured on just about everything except the one issue Romney can win on: jobs -- which is why it won't change the outcome of the 2012 election.

The 2012 election forecast: Obama, 302 electoral votes; Romney, 236.