In a bid to seize Senate leadership in 2014's midterm elections, Democrats and Republicans have been mounting costly and aggressive campaigns manned by national and independent political groups in North Carolina.

The state is one of the eight Senate contest seats CNN rates as "up for grabs" during this year's elections.

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The Republicans are eyeing to retake Senate leadership by slating Thom Tillis against the more popular incumbent Democratic Sen. Kay Hagan. GOP needs at least six seats to net Senate majority, USA Today reported.

According to CNN's polls, Hagan received 46 percent favorable rating, suggesting that nearly half of the voters like her and will vote for her, versus Tillis who only got 43 percent in the polls.

National political parties supported by independent groups are racing to sway North Carolina's voters in what USA Today describes as one of the most expensive Senate elections in the country.

Already, the cost of the race has amounted to US$30 million on expenses in television advertisements alone. Various groups such as Planned Parenthood have been spending more on field operations.

Another group, the pro-Tillis Americans for Prosperity (AFP) launched last year its most aggressive television advertising campaign to date. In addition, the group began a massive call campaign in April this year and has targeted a weekly minimum of 13,500 house visits.

Meanwhile, the Democrats, who seek to boost their narrow three-point lead against the Republican challenger, have been doubling down on their field operations in the state as part of a national strategy to secure higher electoral turnouts.

According to USA Today, the Democrats already have 10,000 volunteers working behind Hagan's campaign.

The state of North Carolina may prove to be a real game changer as it has seen sharp deviations from normal electoral turnouts in the recent elections.

In 2008, President Barack Obama became the first Democratic presidential candidate to win in the state in years. However, in the following midterm elections, democrat supporters opted to miss the elections.

"This is potentially ground zero for who controls the Senate," Steven Green, a political scientist, told USA Today.

TagsU.S. midterm elections, midterm elections 2014 North Carolina, North Carolina Senatorial elections, U.S. politics