Barbara Anderson, a veteran anti-tax activist, plans to endorse state Representative Daniel B. Winslow for US Senate on Tuesday, a nod that could help Winslow win the support of fiscal conservatives.
Anderson said Winslow, a Norfolk Republican, has been a strong opponent of Governor Deval Patrick’s proposed $1.9 billion tax increase and has a 100 percent rating from her group, Citizens for Limited Taxation.
“He’s just what we need on fiscal issues,’’ Anderson said.
She plans to formally back Winslow’s campaign for the Republican Senate nomination at a press conference outside the State House on Tuesday.
For decades, Anderson has been at the center of some of Massachusetts biggest tax battles. In 1980, she helped lead the charge for Proposition 2 ½, a ballot measure limiting property tax increases and, in 2000, helped pass an initiative petition to roll back the state income tax rate.
Anderson said she is backing Winslow over one of his rivals, former US attorney Michael J. Sullivan, because even though both candidates are strong fiscal conservatives, Winslow’s support for abortion rights and gay marriage reflects her own views on those issues.
Sullivan opposes legalized abortion and has said states should be allowed to decide whether to ban gay marriage.
“The social issues are getting more important to me,’’ Anderson said. “I worry about social conservatives hurting our chances to save the country and the world, and I don’t understand the opposition to gay marriage.’’
Anderson said she was initially intrigued by the third Republican in the race, former US Navy SEAL Gabriel E. Gomez, but ruled him out because of the letter he wrote to the governor in January asking Patrick to appoint him to the interim Senate seat.
In the letter, Gomez pledged to support Obama’s agenda on gun control and immigration — stances he now rejects as a candidate for Senate.
“That did me in,’’ Anderson said. “It makes him seem like someone who would say almost anything to any group… It sounds like political naïveté, but I still don’t like it.’’