DENVER (AP) – A new poll suggests Colorado voters might be ready to extend legal benefits enjoyed by married couples to same-sex couples while amending the Constitution to ban same-sex marriage, but are likely to turn down a proposal to legalize adults’ possession of small amounts of marijuana.

The poll of 625 registered voters conducted last week for The Denver Post by Mason-Dixon Polling & Research also showed respondents favoring a plan requiring school districts to spend 65 percent of their budgets on activities that directly affect student instruction. The poll had a margin of error of plus or minus 4 percentage points.

It indicated that few respondents remained undecided about Amendment 44 on marijuana possession, Amendment 43 on same-sex marriage and about Referendum I on domestic partnerships.

And despite all the money spent on campaigns, voters have largely stuck to their first impressions on those measures, the poll suggested. The results of last week’s poll varied only slightly from a similar poll conducted in February.

“There is usually not a ton of movement,” said University of Denver political scientist Seth Masket. “There is a rule of thumb that if an initiative, shortly before an election, is at less than 50 percent … it is fairly unlikely to pass.”

Amendment 44 on marijuana possession had support from 34 percent of respondents while 57 percent opposed it.

Mason Tvert, who heads the Safer Alternative for Enjoyable Recreation campaign for the proposal, criticized the poll’s method, saying few people under 30 years old have land-line telephones, meaning pollsters were unable to reach them.

While Masket said he wasn’t surprised that poll respondents appeared to favor both the measure to create domestic partnerships and the proposal to amend the Constitution to define marriage as a union of one man and one woman, but said it was unlikely that the same voters were supporting both measures.

Amendment 43, to ban same-sex marriage, was favored by 51 percent of respondents and opposed by 43 percent. Referendum I, to create domestic partnerships, had support from 47 percent of respondents and was opposed by 42 percent.

Support for both fell largely along party lines, with Democrats favoring Referendum I 73 percent to 19 percent, and Republicans favoring Amendment 43 68 percent to 30 percent.

Among unaffiliated respondents, 46 percent favored Amendment 43 while 45 percent opposed it; and half supported Referendum I while 38 percent opposed it.

Sean Duffy, who heads the campaign for the domestic partnerships referendum, said he has focused on people likely to vote for both measures, tailoring its communications to appeal to those who oppose same-sex marriage but wish to grant basic legal rights to same-sex couples.

“It’s a substantial amount of people in Colorado,” he said. “It’s moderate Democrats, it’s Republicans, Independents.”