Business groups plan to go on offense against vulnerable Senate Democrats in their backyards to mark Monday's Labor Day holiday.

Local groups will target Senate Majority Leader Harry ReidHarry Mason ReidTrump presses GOP to change Senate rules Only thing Defense’s UFO probe proves is power of political favors Nevada Democrat accused of sexual harassment reconsiders retirement: report MORE (D-Nev.), Sen. Michael BennetMichael Farrand Bennet2020 Dems unify around assault weapons ban, putting pressure on colleagues McConnell, Schumer tap colleagues to explore budget reform Democrats march toward single-payer health care MORE (D-Colo.), Rep. Paul Hodes, the Democrat running for Senate in New Hampshire, and Kentucky Senate Democratic candidate Jack Conway in their states over their records on labor-related issues.

Local chapters of groups like the National Federation of Independent Business, state Associated Builders and Contractors and other commerce and retail groups will hold events on Monday targeting the incumbents and candidates, particularly on their stance on the Employee Free Choice Act (EFCA, or "card-check").

The events are part of coordinated efforts by the business groups to put pressure on Democrats on Labor Day, a national holiday traditionally celebrated by the organized-labor community.

The events also serve as a rejoinder to the events unions have planned throughout the long weekend to bolster some of their candidates. Top AFL-CIO officials, for instance, will be in California and Florida, among other places, and AFL-CIO President Richard Trumka will appear at a labor rally on Monday alongside President Obama and Secretary of Labor Hilda Solis.

Both business and labor groups are planning to be heavily involved — and to spend heavily — in this fall's crucial midterm elections, especially after a Supreme Court ruling earlier this year removed some restrictions on their spending on behalf of candidates.