Filming candidates' homes. Following them into grocery stores. Using hidden cameras. 

These "intimidation" tactics, which are being employed more frequently by aggressive political campaigns, have to stop, according to two lawmakers who made a bipartisan appeal this week to rein in so-called "trackers." 

Rep. Dennis Kucinich, D-Ohio, and Rep. Reid Ribble, R-Wis., have fired off a letter to the heads of the Republican and Democratic congressional campaign committees. In it, they decried the tactics used by campaign operatives that roam around with video cameras trying to catch rival candidates in a compromising position. 

"Sometimes it even borders on stalking," the lawmakers wrote. 

They said campaigns are within their right to send trackers to each others' events, but "we strongly believe a person's family or private property should be off limits to both sides and that the growing use of trackers as an intimidation tool has no place in our electoral system."