Voters in the US say health care, unemployment, the federal deficit, international issues and gas prices will help influence their decision ahead of the presidential election -- but just one in five thinks birth control policies are an important factor, a Gallup poll out Monday found.

The poll also saw President Barack Obama record his biggest lead yet over Republican frontrunner Mitt Romney after voters were asked who they would vote for were an election held today.

Forty-nine percent said they would vote for Obama, while 45 percent would choose his likely opponent Romney. The pair were tied at 47 percent in the last poll taken in mid-February.

The government's birth control policies have received significant coverage recently, particularly provisions under "Obamacare" that would require some religious institutions to offer birth control as part of their health insurance plans.

Republican candidates and religious leaders have criticized the provision, while Obama has defended it.

Just 20 percent of those polled said policies on birth control would be extremely important to their vote, while health care, gas prices and unemployment were seen as extremely important by almost double that number -- 39 percent.

The federal budget deficit and national debt was extremely important to 44 percent of respondents.

Democrats are significantly more likely than independents or Republicans to say birth control policies will be important to their vote, but even among Democrats, the issue comes in last on the list of those they were questioned about.

The differences could be partly due to women being more likely than men to identify as Democrats, as women voters are significantly more likely than men to rate government policies relating to birth control as important, Gallup said.

Twenty-eight percent of respondents said they agreed with the views of Obama on government policies concerning birth control, while Romney and Rick Santorum's views were seen positively by just 12 percent and 13 percent respectively.

Sixty-five percent said they did not know enough about where Romney stands on the issue to form an opinion, while 56 percent said the same of Santorum.

In another result of the poll, 42 percent of registered voters nationwide said they were "extremely" or "very enthusiastic" about voting for president in this year's election. That is down significantly from 52 percent in January.

The decline is especially apparent among Romney voters, whose enthusiasm has fallen 13 percentage points from January, and now is on par with Obama voters' enthusiasm.

The decline in Romney voters' enthusiasm mirrors the trend in enthusiasm among Republican registered voters, which is down 12 points since January, 61 percent to 49 percent. Democratic registered voters' enthusiasm has dropped a smaller seven points, 58 percent to 51 percent.

The poll was conducted March 25-26 with a random sample of 901 registered voters. The poll has a margin of error of four percentage points.