Indian Wells, California (CNN) The influential Koch network plans to invest close to $400 million toward protecting Republican majorities and promoting policy priorities in the 2018 midterm election cycle, the network's leaders say -- roughly a 60% increase over the group's 2016 spending.

Billionaire Charles Koch challenged donors and leaders "to increase the scale and effectiveness of this network by an order of magnitude, by another tenfold."

"Because if we do that," Koch said this weekend, "I'm convinced we can change the trajectory of this country."

The network had previously indicated it was to spend between $300 million and $400 million toward both policy and political objectives. The spending target was previously announced last summer; the network's leaders stressed Saturday that they now anticipate hitting the top of that range by Election Day.

"This network is going to have the largest investment we've ever had in a midterm election in 2018," Tim Phillips, president of Americans for Prosperity, one of the groups under the Koch umbrella, said Saturday. "So, we're all in."

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