(California) - In a race that has put the new Top Two primary system to the test, Democrat Eric Swalwell, 31, challenged long-time incumbent Democrat Pete Stark, 81, for the 15th Congressional District. With 42% of the vote counted, Swallwell is leaded with over 55% of the vote. More than half the votes are still left for counting, but as of now, it appears Swalwell has won California's new non-partisan primary battle against the incumbent.

[Eric Swallwell has officially defeated the incumbent with just over 53% of the vote]

Stark, 81, has held his seat since 1972 and was, perhaps for the first time in his career, required to seriously defend his post. The race was one of the most divisive and nasty races in California, as each candidate took personal jabs at one another in an effort to undercut their credibility.

Opponents of California's top-two open primary system argue that a situation where two members of the same party on the general election ballot would leave voters without a choice. Perhaps, the 15th Congressional District is the first example of where Republican and Independent voters in a predominately Democratic district have had a choice for the first time. Under the old system, Swalwell would have been defeated in the primary and Stark would have coasted into another term. Not this year.

Swalwell and Stark may be from the same party, but they do differ on policy and practice.  Swalwell insisted that the district needed “new energy and ideas.” Swalwell, 50 years the junior of his opponent, had great success in resonating with constituents and appealing to voters across party lines.

Stark is known to be one of the most partisan members of California’s congress and had a turbulent and bizarre campaign. In October, Swalwell said: "He's not up for the job and it's time to move on. You have to be connected and on the ground and he's been absent and asleep at the wheel."