Two independent expenditure committees funded in part by wealthy supporters of charter schools are wrapping their spending sprees on Senate Republican candidates with large ad purhcases in two state Senate races upstate.

In the last three days, New Yorkers For A Balanced Albany and Balance New York spent a combined $576,255 to support Republican candidates in key races.

The group New Yorkers For A Balanced Albany over the weekend posted a $350,000 ad purchase in the race to boost Republican Terrence Murphy, who is competing against Democratic candidate Justin Wagner for the open Hudson Valley district being vacated by Sen. Greg Ball, a Republican.

The group also spent $12,555 polling the Wagner-Murphy race, as well as the contest between Republican Sen. Jack Martins and his opponent, Adam Haber.

Balance New York, meanwhile, poured more resources into the 46th Senate district, where Democratic incumbent Cecilia Tkaczyk faces a rematch against Republican former Assemblyman George Amedore.

The group reported spending $30,000 on web ads attacking Tkaczyk and $195,000 on TV ad purchase aimed at backing Amedore.

Outside groups are pouring millions of dollars into the fight for the state Senate, and it’s estimated so far they have spent $14 million as lawmakers next week will consider a range of contentious issues from expiring rent regulations to mayoral control of New York City schools.