Prior to 2006, his public profile consisted in his highly decorated combat experience in Vietnam, a stint as Ronald Reagan’s Secretary of the Navy and a successful career as an author. His opposition to the Iraq war, and his unconcealed disgust with the way that the Bush administration started and prosecuted it, propelled him into national politics along with his evident dissappointment that lower-middle and working class Americans weren't sharing in the prosperity associated with the Bush recovery.
Here’s how Webb described his decision to run for the Senate as a Democrat in a 2007 interview with NPR (my emphasis):
“I grew up in a family that was Democratic. And I went over to the Republicans, like a lot of people did at the end of the Vietnam War, based on national security issues. And again, like a lot of people, I was never comfortable with the Republican Party platform as it related to economic fairness, and some issues of social justice.There’s no denying that Webb was standing on firm historical ground when he spoke of the “Jacksonian wing” of the Democratic Party. It makes perfect sense to call the most accomplished liberal presidents of the last century, FDR, Harry Truman and LBJ, “Jacksonian Democrats.” But what other Jacksonians were left in the Democratic congressional caucus for Webb to pal around with once he got to the Senate? I suppose there was Harry Byrd, but who else? Maybe Webb's leaving because he's lonely.
“The last book that I was writing ... [a] nonfiction book about the Scotch-Irish migration ... [was] basically about the creation of populist-style democracy in the United States, Jacksonian democracy. [It] caused me to do a lot of thinking about where both political parties are. And when I decided to run, I felt most comfortable with, shall we say, the Jacksonian wing of the Democratic Party. And this is why I decided to run as a Democrat.”
There still is, to be sure, a Jacksonian Democratic constituency. Those are the voters Hillary Clinton was courting in the 2008 Democratic presidential primaries when she was knocking back all those boilermakers in working class bars and sharing her childhood memories of discharging firearms in the backyard of her family’s vacation cabin. Another name for them is “Reagan Democrats.”