A single paragraph from Kennedy's famous 1960 address to Southern Baptist leaders shows any similarities end there:

"I believe in an America where the separation of church and state is absolute; where no Catholic prelate would tell the President -- should he be Catholic -- how to act, and no Protestant minister would tell his parishioners for whom to vote; where no church or church school is granted any public funds or political preference, and where no man is denied public office merely because his religion differs from the President who might appoint him, or the people who might elect him."

But on Thursday, Mitt Romney cannot utter these words or anything remotely like them. Not, as Romney said Monday, because "times have changed" since his father ran for President in 1968. And not merely because they are anathema to increasingly conservative Republican primary voters (a third of whom are evangelicals). No, Mitt Romney can't echo John F. Kennedy's words because he simply doesn't believe them.

Unlike Kennedy, Mitt Romney himself is largely responsible for making his religion a campaign issue. Romney's self-made trap began with his 2006 declaration that religious faith is in essence a prerequisite for being President of the United States. "People in this country,' Romney told Fox News, "want a person of faith to lead them as their president." Having proclaimed religiosity a requirement for the occupant of the White House, Romney then compounded his problems by blurring the distinctions between his Mormonism and mainline Protestant faiths (often to the dismay of his own co-religionists). As Josh Patashnik wrote in the New Republic, Romney has repeatedly downplayed fundamental Mormon doctrines including the Baptism of the Dead and the past and future visits of Jesus Christ to America.

Digging his hole deeper, Romney just last week made it clear he parted company with John F. Kennedy - and the United States Constitution - by proclaiming a religious test for service in a future Romney cabinet. As he told Mansoor Ijaz, Muslim Americans need not apply:

I asked Mr. Romney whether he would consider including qualified Americans of the Islamic faith in his cabinet as advisers on national security matters, given his position that "jihadism" is the principal foreign policy threat facing America today. He answered, "...based on the numbers of American Muslims [as a percentage] in our population, I cannot see that a cabinet position would be justified. But of course, I would imagine that Muslims could serve at lower levels of my administration."

(Despite Romney's protestations that he was misquoted, Ijaz stands by his account. Others reports of Romney's anti-Muslim bias have also surfaced since.)

Given the roughly comparable numbers of Muslims, Jews and Mormons in the United States, Romney's prohibition against Islam in the Cabinet is especially dangerous and self-defeating. Again, Kennedy's 1960 admonition fell on deaf ears in the Romney camp:

"For while this year it may be a Catholic against whom the finger of suspicion is pointed, in other years it has been -- and may someday be again -- a Jew, or a Quaker, or a Unitarian, or a Baptist. It was Virginia's harassment of Baptist preachers, for example, that led to Jefferson's statute of religious freedom. Today, I may be the victim, but tomorrow it may be you -- until the whole fabric of our harmonious society is ripped apart at a time of great national peril."

Despite suggesting as early as July that he would speak to Americans on the subject of his Mormon faith, the Romney camp was desperate to avoid giving this speech before the GOP primaries were over, if ever. (While in July Romney proclaimed, " I haven't made a final decision, but it's probably more likely than not," by early November he had changed course, "the political advisors tell me no, no, no, it's not a good idea. Draws too much attention to that issue alone.")

But now Team Romney has no choice. With former Arkansas Governor and Baptist minister Mike Huckabee catapulting past him in Iowa, Mitt Romney's entire 2008 campaign strategy is unraveling. Counting on the "Iowa Effect," Romney was counting on a strong showing in the Iowa Caucus to propel him through New Hampshire and South Carolina, producing a media-fed momentum wave that would wash over Rudy Giuliani's national campaign. But stiff competition from Huckabee, whose campaign is capitalizing on concerns among Iowa evangelicals about Romney's Mormonism, risks derailing Romney out of the gate. For Mitt Romney, it's now or never.

And so Thursday Mitt Romney will go to the George H.W. Bush presidential library in Texas in hopes of repeating John F. Kennedy's feat in 1960. (Romney's emulation of his Massachusetts predecessor even goes so far as choosing the Lone Star State as the location for his make-or-break speech.) But Romney's task is far different than JFK's. Kennedy made it clear he wanted to defuse the religion issue altogether:

"While the so-called religious issue is necessarily and properly the chief topic here tonight, I want to emphasize from the outset that I believe that we have far more critical issues in the 1960 campaign..."

Clearly, Mitt Romney wants to follow JFK down that path. On Monday, Romney previewed his talk, titled "Faith in America":

"I can tell you I'm not going to be talking so much about my faith as I am talking about the religious heritage of our country and the role in which it played in the founding of the nation and the role which I think religion should generally play today in our society."

Sadly for Romney, it's too late for a history lesson. When John F. Kennedy said, "I do not speak for my church on public matters -- and the church does not speak for me," he had not made religious faith a sine qua non of his campaign. He famously met with Baptist leaders to explain that his Catholic faith, one shared by tens of millions of Americans, would not govern his decisions as President. But after declaring religious faith a prerequisite (in the case of Muslims, a firm barrier) for office, Mitt Romney must now discuss his own, one which remains a mystery to most Americans.

As for Mitt Romney, I've read and heard the speech by John F. Kennedy. Governor, you're no Jack Kennedy.

UPDATE: Satirical Political has another take on the Romney/JFK comparison.