The state of Michigan has joined the US Department of Justice's case to block Oracle's proposed takeover of PeopleSoft.
Michigan becomes the eighth state to join the case, which is expected to commence trial in June.
A merger between Oracle and PeopleSoft would hurt industry competition and increase the cost of related goods and services for Michigan businesses.
The reduced competition could cost Michigan residents $130m (£612m).
Oracle's campaign to acquire PeopleSoft in a hostile takeover now valued at $9.4bn faces a number of obstacles, the most urgent of which is the DOJ's lawsuit seeking to prevent the deal.
The European Commission could also thwart Oracle's ambition to consolidate the market for ERP software. The organisation is set to rule by 11 May on whether it would allow the two companies to combine.
Stacey Cowley wrties for IDG News Service