Gene J. Puskar/AP Photo

On Rick Santorum's decision to suspend his campaign, a few pertinent points from our polling:

• Santorum's move reflects his diving poll numbers within the GOP. In our latest ABC/Post poll, out this morning, Republicans and Republican-leaning independents preferred Mitt Romney over Santorum for the nomination by 42-22 percent. That 20-point gap in Romney's favor had widened from a mere 2 points, 31-29 percent, a month ago.

• Half of Santorum's supporters go to Romney. Our poll had it 42-22-17-10, Romney-Santorum-Paul-Gingrich. When we reallocate using Santorum's voters' second choice, Romney gains 11 points, Gingrich 7, Paul just 3. New standings: Romney 53 percent, Paul 20, Gingrich 17.

In the primaries, Santorum never could effectively break out of his very conservative, highly religious base. Four examples:

• Across all primaries for which we have exit poll data, among evangelicals, 52 percent of the electorate, Santorum beat Romney by a scant 3 points. But among non-evangelicals Romney beat Santorum by 29.

• Santorum came within 6 points of Romney among very conservative voters, about a third of the electorate. But Santorum lost the other two-thirds to Romney - somewhat conservatives, moderates, the few liberals - by a far wider 22 points.

• Among voters who were focused "a great deal" on a candidate who shares their religious beliefs, Santorum beat Romney by 26 points. But among all others - 70 percent of GOP voters overall - Romney beat Santorum by 17.

• Among voters who said abortion should be illegal in all cases, Santorum beat Romney by 13 points. Among all others, though, Romney finished ahead of Santorum by 18 points - and, again, they were the far larger share, accounting for 76 percent of GOP primary voters.

For all this, back to our latest ABC/Post poll, while leaned Republicans preferred Romney over Santorum by a vast 36 points to handle the economy, they divided essentially evenly on which of the two would best handle social issues such as gay marriage and abortion - Santorum, 29 percent, Romney 27. That marks the ideological shortfall that's troubled Romney all year - but also underscores that, for Santorum, strongly conservative credentials never were quite enough.