A hotly contested Senate race means tons of money spent, and both the Democratic Senatorial Campaign Committee and the National Republican Senatorial Committee continue to back their respective candidate, Sen. Michael Bennet and Ken Buck, while other states are deemphasized in the final weeks of the campaign:

To date, the DSCC’s spending has focused on the set of races that are genuinely balanced on a knife’s edge, according to Federal Election Commission data. Through the end of September, the committee had put $3.1 million into Colorado, where incumbent Sen. Michael Bennet is about evenly matched with Republican challenger Ken Buck, and $3.2 million into Pennsylvania, where Rep. Joe Sestak trails Republican Pat Toomey by single digits. It has also spent substantial sums to retain seats in Connecticut, Illinois and West Virginia, and to flip Republican-held seats in Missouri and Kentucky. […]
So when it comes to campaign spending, the NRSC is leaning most heavily into those races that would take it from picking up about five seats to gaining eight to 10 seats. It’s already spent or committed independent resources in the Democratic-held states of Colorado, California, West Virginia, Illinois and Washington. And it has marked off seven-figure sums for coordinated spending in several additional states, including Pennsylvania and the Republican states of Kentucky, Missouri and Florida.

Via the Washington Post, updated third-party expenditures have now topped $15,413,459–with $5,414,268 in just the past week.

The Post breaks that down to $9.2 million benefiting Republicans (including the primary), and nearly $6 million for Democrats.

The following document lists the group, which candidate the groups supports or opposes, the amount expended in the past week, and the total amount spent this cycle.

Oct Outside Expenditures Senate