A Reuters/Ipsos poll published Tuesday shows Ted Cruz climbing to within a few points of Donald Trump nationally among Republicans. Because the gap is within the poll’s margin-of-error, Reuters is calling it a dead heat:

Cruz got 35.2 percent of support to Trump’s 39.5 percent, the poll of 568 Republicans taken April 1-5 found. The numbers put the two within the poll’s 4.8 percentage-point credibility interval, a measure of accuracy.

Cruz, a U.S. senator from Texas, and Trump were also briefly in a dead heat early last week. But as recently as a month ago, when Senator Marco Rubio was also still a candidate, Cruz trailed Trump in Reuters/Ipsos polling by about 20 points.

Reuters notes that only one other candidate has come this close to Trump and that was Ben Carson back in November. However, more striking is Cruz’s surge among likely Republican primary voters. Allahpundit pointed earlier to Reuters 5-day-rolling poll average which shows Cruz overtaking Trump among likely voters. That shift happened Monday and here is where things stand today (Reuters graphic):
Reuters April 5

Finally, when you look at Republicans likely to vote in the general election you get this result:

General April 5

Again, that dead heat has only existed since Monday and the movement in the numbers seems to have happened over the past week. But why now? Marco Rubio has been out of the race for 3 weeks so whatever case Cruz could make for being the best anti-Trump candidate would presumably have sunk in before now. Could it be awareness that there is a real chance Trump won’t get to 1237 delegates? That possibility has been in the news more in the past few days with the approach of the Wisconsin primary. Still, the idea that this could go to a contested convention has been floating around for weeks.

This could be a moment where the dynamic of the race, which has been fairly steady as far as Trump is concerned, finally shifts. Then again, we could see Trump’s numbers rebound in a few days and the whole thing will look, in hindsight, like just another statistical blip on his path to the nomination. All we can say for certain is that Cruz’s rise this week is about as close as anyone has come to making Trump look vulnerable.