FULLERTON (CBSLA)  — A major new poll out today shows California Democrats leading or tied with Republicans in five hotly-contested house races.

A blue wave in California would help the democrats potentially wrest control of the house back from the republicans.

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CBS2’s Michele Gile reported from Fullerton where former Vice President Joe Biden was to attend an event for democrats eager to flip the house.

One local political expert is calling these races some of the most interesting and exciting in 50 years.

For the democratic candidates — feeling anything but blue in the conventional sense — they told Gile they were excited to have a big party heavyweight like Biden stumping for them so close to election day.

Last month was Barack Obama’s turn. He attended a rally with the candidates hoping to flip those seats.

Today’s poll shows democrats leading or tied in seats they haven’t held for decades.

(credit: JANEK SKARZYNSKI/AFP/Getty Images)

“First and foremost,, of course, Californians voting on November 6th,” says Ange-Marie Hancock Alfaro, a USC political science and gender professor, “is going to mean more than it’s meant in a really long time for national politics. It also means there is going to be more media attention in these five races than there usually is in any congressional race in the state of California.”

The poll was conducted by the LA Times and UC Berkeley.

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In the 25th congressional district, democrat Katie Hill leads Steve Knight, 50-46%

In the 39th, democrat Gil Cisneros has a 49-48% lead over republican Young Kim.

“Suburban voters nationwide have shifted sharply to the democratic column,” says Jack Pitney of Claremont McKenna College. “And that’s why democrats are so hopeful.”

In the 45th district, democrat Katie Porter is leading incumbent republican Mimi Waters by 52-45%

In the 48th district, incumbent Dana Rohrabacher (in office for nearly 30 years) is tied with democratic challenger Harley Rouda, 48-48%

In the 49th district, democrat Mike Levin had a commanding lead over republican Diane Harkey, 55-41%

According to the political expert, in each race Donald Trump is a key factor.

“The democrats make this a referendum about Donald Trump,” says Pitney, “and if it’s a referendum on Donald Trump, democrats win.”

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One local political scientist says that the democrats can likely flip one or two seats — and as many as seven in California next month. That would change the landscape politically locally but also nationally.