Rep. Marcy Kaptur edged out fellow Democratic Rep. Dennis Kucinich (Ohio) in a primary on Tuesday, leaving no clear path forward for Kucinich to remain in Congress.

It was a humbling loss for the eight-term congressman, who built a national following, twice ran for president and established himself as a forceful voice for the liberal wing of the Democratic Party. But he faced a tough task in defeating Kaptur. 

The swath of Ohio that brought Kaptur and Kucinich into battle runs along the coast of Lake Erie, spanning from Kaptur’s home base in Toledo to Kucinich’s stronghold in Cleveland. A last-minute change to the map, put into place by Republican state lawmakers, added more of Kaptur’s Toledo-area constituents to the new district, giving her a built-in advantage.

Neither Kaptur nor Kucinich sought out the fight. Drawn into the same district by GOP mapmakers, the two friends and House allies were forced to square off in the first of about a dozen redistricting-induced primary showdowns.

With 100 percent of precincts reporting, Kaptur captured 56 percent to Kucinich’s 40 percent. A third Democratic candidate, businessman Graham Veasey, placed last with 4 percent.

"This was a very intense campaign, because of the way the district was drawn," Kaptur said on MSNBC. "We had to advertise in two media markets, the new one being five times more expensive than the existing one. It was just a real marathon."

Kaptur said she had not yet spoken to Kucinich.

Kaptur will face Republican Samuel Wurzelbacher, better known as "Joe the Plumber," in the general election. Wurzelbacher was given the moniker by the McCain-Palin presidential campaign, who in 2008 used Wurzelbacher as an example of disenfranchised blue-collar voters. He won the GOP primary by 51-49 over Steven Kraus.

A 14-term congresswoman and the longest-serving female member of the House, Kaptur is poised to easily win reelection in November in the redrawn, Democratic-leaning district.

But for Kucinich, this could be the end of the line.

Ohio lost two seats in the House following the 2010 U.S. Census. When it became clear last May that Kucinich’s district would likely be on the chopping block, he toyed with the idea of running in an open district in Washington state instead.

Kucinich hasn’t completely ruled out a bid in Washington, but the blowback he faced for appearing nonchalant about his commitment to Ohio constituents highlighted the political difficulty of making such a move. Kaptur used that vulnerability time and again in the short but hard-fought primary to knock Kucinich for being more concerned about his own career than his service to Ohio.

The two Democrats had similar voting records in the House and found little about each other to quibble with — until each one’s political career became dependent on the other’s demise. Kucinich reminded voters that Kaptur had voted for continued war funding in Iraq and Afghanistan, while Kucinich voted against it. Kaptur claimed Kucinich had let down his district by failing to bring home the goods when federal stimulus dollars were divvied up.

Kaptur’s primary win gives her an opportunity to claim another highly coveted prize. Rep. Norm Dicks (D-Wash.), the top Democrat on the House Appropriations Committee, announced Friday his plans to retire. Kaptur is next in line for the top spot on the all-powerful committee, and could find herself the chairwoman if Democrats flip control of the House in November.

Two other members of Ohio’s congressional delegation, Republican Rep. Jim Renacci and Democratic Rep. Betty Sutton, were also pitted against each other by redistricting and will square off in November’s general election.

- This post was updated at 12:51 a.m.