President Donald Trump (L) talks with U.S. Sen. Dean Heller (R-NV) during a campaign rally at the Las Vegas Convention Center on September 20, 2018 in Las Vegas, Nevada.

Endangered Republican Sen. Dean Heller holds only a slight edge over Democratic Rep. Jacky Rosen in a Nevada Senate race that Democrats see as one of their best chances to flip a Senate seat.

Heller leads Rosen by only 2 percentage points among likely voters, according to a new NBC News/Marist College poll released Tuesday. The survey shows Heller garnering 46 percent of support from Nevada voters, while Rosen has backing from 44 percent, within the 5.5 percent margin of error.

The Nevada contest is one of the most important in a year when Republicans will keep their Senate majority if they stop Democrats from gaining two seats in the chamber. Health care has ranked as the top issue in Nevada for most of the campaign. But Brett Kavanaugh, who became a Supreme Court justice on Saturday despite facing several sexual misconduct accusations, has divided the candidates most sharply in recent days.

Heller voted for Kavanaugh's confirmation, while Rosen denounced it. Before the confirmation, Heller drew national media attention when he said the first assault allegation against President Donald Trump's nominee would just be a "hiccup" in his rise to the court. Rosen ran digital ads attacking the senator for his support of Kavanaugh.

Voters remain largely divided on the issue, and it's unclear now how much Kavanaugh's confirmation will affect the race's outcome. The poll shows that 41 percent of likely voters would be more likely to vote for a candidate who opposed Kavanaugh versus 38 percent who would rather back a candidate who supported the justice. Eighteen percent say the Kavanaugh confirmation will have no impact on their decision.