State Rep. Dan Winslow's campaign announced on Sunday that he has collected 25,000 signatures in his drive to join the GOP primary ballot. Though by law, candidates must collect at least 10,000, the usual aim is up to 20,000 signatures, because many are thrown out as invalid.

“I am honored and encouraged that nearly 25,000 people from the Commonwealth of Massachusetts have helped me take the first step in my campaign for the United States Senate," Winslow said in the release.

His campaign is holding a thank-you event on Monday night for volunteers and staff engaged in the signature-collection effort.

Winslow contributed at least $100,000 of his own money to his campaign, some of which went toward hiring paid staff to collect the signatures needed. One other potential candidate, local businessman Gabriel Gomez, has also hired a firm to help with signature collection.

Former U.S. Attorney Michael Sullivan did not hire a firm to help with that collection, and his spokeswoman told MassLive last week that "it's going to be tough" for the contender to get the necessary signatures to get on the ballot. Collection efforts were stymied somewhat by a winter storm that hit the state this past weekend, the second such storm in a month, which has made it difficult for volunteers to achieve their collection goals.