Pressure is mounting on Newt Gingrich and Rick Santorum to get out of the Republican presidential race, but it really doesn’t matter what they do.

The election math works against them, and neither candidate has a plausible strategy of stopping former Massachusetts Gov. Mitt Romney from collecting the delegates he needs to win his party’s nomination, or of damaging his chances in November.

That means that even though there are months to go before nominating conventions, the general election campaign is under way and it will be a contest between Romney and President Barack Obama, as became clear when both men referred to the other by name in speeches Tuesday.

A Romney aide recently got in trouble for saying that the campaigns reset when they move from intraparty warfare to the general election, comparing it to shaking up an Etch A Sketch to get a blank screen. Opponents jumped on that to mean that Romney would back away from his conservative promises after the primary season ends, but the aide was right: The race will be recast when the real choices stand side by side.

Some Republican “values” voters in the Mississippi primary still might think that Romney is a moderate, but he is not.

He is an advocate for the Paul Ryan budget plan and was endorsed by the Wisconsin congressman, putting Romney firmly in the wing of the Republican Party that wants to cap Medicare and cut Pell grants for low-income students and would have let the auto industry fail

Obama called the plan “thinly disguised social Darwinism” in his speech to the American Association of Newspaper Editors, saying its lack of investment in education and infrastructure was “a prescription for decline.”

When it was Romney’s turn before the editors he said voters would face a “defining decision” about the direction of the country, and promised that Obama would not be able to talk about the future without answering for his administration’s record.

The year-long parade of “not-Mitt” Republican candidates can end. Romney will be his party’s standard bearer. Now the real debate about the proper role of American government in the economy and people’s lives can begin.