Leading Republican lawmakers say in court documents that a lawsuit seeking to close Montana's primary elections intends to keep moderates out of the Legislature.

Senate Majority Leader Matthew Rosendale and House Majority Leader Keith Regier said in depositions filed last week that dissident Republicans thwarted the party's agenda at the 2015 Legislature.

Rosendale says a "distressingly low amount of discipline" among Republicans will only get worse if primaries remain open.

Their statements were added to a lawsuit filed in federal court last year. The lawsuit asks U.S. District Court Judge Brian Morris to strike down a state law allowing voters to participate in any party primary, regardless of party affiliation.

The new filings also include complaints from Republican strategists and former candidates who say Democrats are encouraged to vote in Republican primaries.