GENEVA — A poll released Wednesday suggests Swiss voters are on track to vote yes in a “marriage for all” referendum, which supporters see as a key step for equal rights, but opponents fear could erode traditional family values.

The latest poll for public broadcaster SSR before the Sept. 26 referendum found that 63% of respondents support the measure, with 35% opposed and 2% undecided.

That’s a six percentage point drop in the level of support from a previous poll on the matter published in late August, but suggests the margin remains wide.

Marriage for same-sex couples is not legal in Switzerland, but they can enter registered partnerships.

The Swiss government supports the measure, which would also allow for expedited naturalization of foreign same-sex spouses and grant married women couples access to sperm donation.

The poll of 13,261 registered voters was conducted from Sept. 1-9 and carries a margin of error of plus or minus 2.8 percentage points.