(CNN) - Two of the nation's prominent tea party groups will merge for a Wisconsin bus tour in support of six Republican state senators facing recall elections.
Kicking off their four-day "Restoring Common Sense" tour Friday, Tea Party Nation and Tea Party Express will hold rallies in multiple cities and defend Republicans who supported Gov. Scott Walker's controversial bill that curbed collective bargaining rights for state employees earlier this year.
"The tea party stands for fiscal responsibility, and Republican Senators in Wisconsin stood firm for those principles," said Amy Kremer, chair of Tea Party Express. "Now they are under attack for doing the job they were elected to do. It is critical that we support and defend them from these undeserved attacks and in that effort we are proud to be joined by our friends at Tea Party Nation."
The next round of recalls, scheduled for Aug. 9, is part of a summer long series of elections pitting six Republicans and three Democrats against challengers. An incumbent Democrat already won the first election in July.
If three Republicans can't keep their seats, then the GOP will lose control of the state legislature and Democrats could be poised to overturn Walker's budget reforms.
The Wisconsin budget bill, which was upheld by the state Supreme Court in June, caused sharp division in the state earlier this year. Republicans insisted the measure was needed to control the skyrocketing costs of public employee benefits and close the budget shortfall. Democrats argued that it was an attempt to gut public-sector labor unions, one of their core constituencies.
Under the new law, all public workers, except police and firefighters, would be expected to cover more of their retirement plan contributions and health care premiums on their own.
- CNN Associate Producer Gabriella Schwarz and Political Producer Shannon Travis contributed to this report.