Conservative populist Corey Stewart shocked political observers Tuesday night by nearly upsetting establishment favorite Ed Gillespie in Virginias Republican gubernatorial primary .

Defying polls that showed Gillespie ahead by as much as 20 percentage points , Stewart held Gillespie to a margin of victory of a mere 1.2 percentage points.

Gillespie only narrowly avoided a possible recount challenge. The state permits losing candidates to challenge results when the margin is under 1 percentage point.

The data needed to discern the exact factors behind Stewarts strong performance are still limited, but it appears the Minnesota-born defender of Virginias Confederate heritage and President Donald Trump enthusiast benefitted from the defection of moderate voters from the Republican Party in Northern Virginia.

The share of the Republican primary electorate from the predominantly moderate and affluent suburbs of Northern Virginia declined from 34 percent in the 2016 presidential primary to 30 percent in Tuesdays statewide contest, according to an analysis of official data by Geoffrey Skelley, an expert at the University of Virginia Center for Politics.

There are a lot of moderate, white-collar workers in Northern Virginia who might at one time have been moderate Republicans or independents, but now vote Democratic because they have become functionally Democrats, Skelley said.

The conservative shift of the national Republican Party had been disenchanting those voters for years, according to Skelley, but Trump may have been the final straw for some.