Gallup’s national tracking poll shows Mitt Romney moving out to an 18-point lead over Rick Santorum. Romney is now at 43 percent in a four-man field.

For months Romney antagonists said he was not “closing” the deal or ”consolidating his base.” Truth be told, in a spirited primary with a lot of candidates, that consolidation often comes after the front-runner has virtually put away the competition. In other words, when voters realize their first choice is going nowhere, they get behind the winner. That is what primaries are for, after all — reaching a consensus on the party’s nominee.

Much of the analysis of Romney’s progress in gaining the nomination was built on a shaky premise: those voting for other candidates didn’t like him. Some (many screechy types in the right-wing media) certainly felt that way, but other voters certainly thought they’d see if someone else could win it. Once Romney put Santorum away in a series of key states (Michigan, Ohio, and Illinois), voters “got it” — he’s the nominee. Unlike Santorum, they didn’t need to hang around (with thoughts of a Romney rival dancing in their heads) to know this is how things have wound up.

In fact, looking back to January, Romney’s favorability ratings among Republicans have remained consistently high. The Washington Post-ABC News poll in January, for example — when pundits were convinced he could never break 25 percent — showed his approval with women at 57 percent and with men at 66 percent. Throughout the primary, Romney has ranked high as GOP voters’ second choice.

The same process going on nationally among voters is also happening among elected officials nationally and at the state level. Senate Minority Leader Mitch McConnell (R-Ky.) technically declines to endorse. But yesterday he left no doubt on CNN’s “State of the Union”: “I think he’s going to be an excellent candidate. . . . I think the chances are overwhelming that he will be our nominee. It seems to me we’re in the final phases of wrapping up this nomination. And most of the members of the Senate Republican conference are either supporting him, or they have the view that I do, that it’s time to turn our attention to the fall campaign and begin to make the case against the president of the United States.”

And in Wisconsin the entire Republican Party seems to have wrapped its arms around Romney, as Politico notes: “Local Republicans’ focus on the recall [of Gov. Scott Walker], along with the growing sense that the party is finally coalescing around Romney, has left Wisconsinites a presidential contest largely devoid of the furious back-and-forth that characterized the races elsewhere. Compared to Illinois, the southern neighbor with which Wisconsin carries on a playful rivalry — except when it comes to the serious business of Packers-Bears football games — the Badger State race has been rather calm.”

In most modern presidential primaries, the rivals have magnanimously dropped out when it was clear whom the likely nominee would be. Because Santorum did not and the primary calendar backloaded delegates, the process of consolidation did not happen earlier. But even with Santorum still in the race and hundred of delegates to go, Romney is rounding up support from all parts of the party. That’s because, unlike Santorum, these Republicans understand that Romney will be the nominee and that they better get going with the general-election race.