WASHINGTON — Support for legal abortion in the U.S. has edged up to its highest level in the past two years, according to an Associated Press-GfK poll.

Nearly six in 10 Americans — 58 percent — now think abortion should be legal in most or all cases, up from 51 percent who said so at the beginning of the year, according to the survey. It was conducted after three people were killed last month in a shooting at a Planned Parenthood clinic in Colorado.

While support for legal abortion edged up to 40 percent among Republicans in this month’s poll, from 35 percent in January, the survey found the GOP deeply divided on the issue: Seven in 10 conservative Republicans said they want abortion to be illegal in most or all cases; six in 10 moderate and liberal Republicans said the opposite.

Among Democrats, 76 percent of poll respondents now think abortion should be legal all or most of the time, up slightly from 69 percent in January.

Independents are more evenly split, with 54 percent saying abortion should be legal all or most of the time, edging up from 43 percent in January.

The AP-GfK Poll of 1,007 adults was conducted online Dec. 3 to 7, using a sample drawn from GfK’s probability-based KnowledgePanel, which is designed to be representative of the U.S. population. The margin of sampling error for all respondents is plus or minus 3.4 percentage points.