Rick Santorum’s surprisingly strong triple win in Colorado, Minnesota, and Missouri on Tuesday dramatically improved his national polling. For the first time Santorum has definitively moved into second place, according to a Gallup tracking poll, supplanting Newt Gingrich.

Since Tuesday, Santorum’s polling numbers jumped up 6 points. On Tuesday he was at 16 percent and now he’s at 22 percent. Over the same time period, Mitt Romney’s and Gingrich’s numbers have dropped. Romney went from 37 percent to 34 percent, Gingrich has gone from 22 percent to just 18 percent, pushing him down to third place.

A Fox News poll out today also found that Santorum has moved into second place, thanks to strong momentum from his wins this week. From Fox News:

In interviews conducted on Monday and Tuesday nights — immediately before the news of his victories — Santorum received the backing of 17 percent of GOP primary voters. That was well behind Romney (35 percent) and Newt Gingrich (26 percent), and slightly ahead of Ron Paul (14 percent).

In interviews conducted on Wednesday and Thursday nights — after his wins — Santorum’s support nearly doubled, which put him tied at the top with Romney for those two days at 30 percent. That’s an increase of 13 percentage points. Over the last two nights, Romney also received 30 percent, a drop of 5 points. Gingrich came in at 16 percent, down 10 points. Paul’s support held steady at 15 percent.

In addition to his rising poll numbers, the big wins this week gave him a serious pickup in fundraising. The Santorum campaign claims they brought in over 2 million dollars in donations since his wins were announced Tuesday night.

The momentum is clearly with Santorum right now, but as we’ve seen in this GOP primary, momentum can be remarkably short lived. For now, though, Santorum has a strong opening to make the case to the GOP base that he is the strongest Romney alternative.