Democratic presidential candidate Hillary Clinton holds a conversation on immigration at Culinary Arts Institute of Los Angeles Mission College on June 4, in Sylmar, Calif. | Getty National poll: Clinton's lead slips against Trump

Hillary Clinton’s lead over Donald Trump has dwindled to just 2 percentage points among likely voters in November, according to the results of a national Monmouth University poll released on Monday as the Republican National Convention officially kicked off.

The survey also found voters largely unpersuaded by Bernie Sanders’ endorsement of the presumptive Democratic nominee or the selection of Indiana Gov. Mike Pence as the presumptive Republican nominee’s running mate.


Clinton currently holds the support of 45 percent of likely voters, largely unchanged from the previous month, while 43 percent back Trump, an increase of 6 points from the previous Monmouth survey, in which he trailed by 7 points.

Included as options in the ballot-test question were Libertarian nominee Gary Johnson, whose level of support among likely voters dropped to 5 percent from 9 percent in June, and Green Party candidate Jill Stein, who earned just 1 percent this time, compared with 4 percent in the last survey. An additional 2 percent of likely voters said they would support another candidate, while 4 percent said they were undecided. Among all registered voters surveyed, Clinton’s advantage is 3 points — 43 percent to 40 percent — down from a 6-point lead in June (42 percent to 36 percent) and an 8-point spread against Trump in March (42 percent to 34 percent). Johnson took 5 percent among all voters surveyed, while Stein received 2 percent.

Clinton holds 88 percent support among Democrats surveyed, while Trump has 81 percent of Republicans in his corner, in line with the previous month’s survey. Among independent voters, who were split between Trump and Clinton in June, the Manhattan businessman now leads 40 percent to 31 percent.

The latest results come on the heels of a trio of national polls released Sunday, all of which showed Clinton with a stronger advantage over Trump heading into the two-week stretch of party conventions in Cleveland and Philadelphia. Among registered voters in the ABC News/Washington Post survey that matched the two top candidates head to head, 47 percent supported Clinton to 43 percent for Trump, while 49 percent to 42 percent backed Clinton over Trump in a CNN/ORC International poll, also among registered voters. The NBC News/Wall Street Journal poll of registered voters showed Clinton with a 5-point lead of 46 percent to 41 percent, with 8 percent saying they prefer neither candidate.

Unlike the Monmouth survey, however, the other three polls first asked respondents their opinions on the head-to-head matchup and then introduced Johnson and Stein in a subsequent question. In the other four-way polls, Clinton held leads of 4 points, 5 points and 6 points, in the ABC News/Washington Post, CNN/ORC and NBC News/Wall Street Journal surveys, respectively.

In POLITICO's Battleground States polling average, Clinton maintains a more sturdy lead over Trump, 44.0 percent to 38.8 percent.

According to the Monmouth survey, neither Clinton nor Trump is seen favorably by a majority of registered voters, although Trump’s favorable level increased to 31 percent from 28 percent in June, while Clinton’s dropped by 2 points, 36 percent to 34 percent. As far as whether Sanders’ endorsement of Clinton last week would matter, 73 percent of all registered voters said it would have no impact, while 17 percent said it would make them more likely to support the former secretary of state and 9 percent less likely.

More than three-quarters of the registered voters surveyed(76 percent) said the selection of Pence would not affect their vote, while 11 percent said it would make them more likely to vote for the Republican ticket and 10 percent less likely.

The poll was conducted via landlines and cellphones from July 14 to 16, surveying 805 registered voters with an overall margin of error of plus or minus 3.5 percentage points. Among the 688 likely voters, the margin of error is plus or minus 3.7 percentage points.