WASHINGTON -- With the first of the nominating conventions less than a week away, the latest NBC News/Wall Street Journal poll adds more evidence that the choice of Paul Ryan as Mitt Romney's running mate has not been a "game changer" in the 2012 race for the White House.

The latest poll of 1,000 registered voters nationwide, surveyed from Aug. 16 to 20, found President Barack Obama with a narrow 4 percentage point lead (48 to 44 percent) over presumptive Republican nominee Mitt Romney. That's slightly narrower than the previous NBC/WSJ poll in July, which showed Obama leading by 6 points (49 to 43 percent). Support for each candidate in the newest survey fell within the margin of sampling error.

That new result squares with the HuffPost Pollster chart, based on all available public polls, which shows no significant change in the Obama-Romney race since the spring.

Separately, a polling tracking model created by political scientist Simon Jackman exclusively for The Huffington Post finds that as of Monday, national-level vote preferences were "virtually unchanged" since Ryan's selection and remain "all but indistinguishable from where they have been for months."

Beyond vote preferences, the NBC/WSJ poll also found that Romney's selection of Paul Ryan "had less of an impact on voters than previous running mates have had." Roughly the same number said Ryan's selection made them more likely to support the Republican ticket (22 percent) as said they were less likely (23 percent), with more than half (54 percent) saying it made no difference. According to NBC, "that margin (-1) is compared with Joe Biden's in 2008 (+8), Sarah Palin's in 2008 (+9 percent), John Edwards' in 2004 (+21), and Joe Lieberman's in 2000 (+13)."

The poll also asked about the Ryan proposal to "change how Medicare would work so seniors being enrolled in the program ten years from now would be given a guaranteed payment some call a voucher from the federal government." Given descriptions of the positions of both Romney and Obama, 54 percent said they agreed more with Obama and only 34 percent said they agreed more with Romney.

Also on HuffPost:

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  • Wealthy Benefit Most From Tax Cuts

    Paul Ryan's most recent budget proposal would save those making between $20,000 and $30,000 just $246 in taxes, compared to savings of $265,011 for those who make over $1 million, according to analysis from the <a href="http://www.washingtonpost.com/business/economy/2012/04/02/gIQAjn0grS_graphic.html" target="_hplink">Center on Budget and Policy Priorities</a>.

  • Health Care Cuts

    The "Path to Prosperity" would cut $2.4 trillion from Medicaid and other health care programs for people with low or moderate incomes, according to analysis from the <a href="http://www.washingtonpost.com/business/economy/2012/04/02/gIQAjn0grS_graphic.html" target="_hplink">Center on Budget and Policy Priorities</a>.

  • Fewer People Covered By Medicaid

    Under Ryan's "Path to Prosperity" as many as 44 million fewer people would be covered under Medicaid, <a href="http://www.cbsnews.com/video/watch/?id=7417870n" target="_hplink">according to CBS News</a>.

  • Reduced Health Care For Retirees

    Ryan would raise the age of Medicare eligibility from 65 to 67. If the Affordable Care Act was repealed, something Romney has pledged, that means many 65- and 66-year-olds would be left uninsured, the <a href="http://mediamatters.org/research/2012/08/11/seven-things-the-media-needs-to-know-about-paul/189277" target="_hplink">CBPP reports</a>.

  • Seniors Would Pay More For Health Coverage

    Under Ryan's "Path to Prosperity," senior citizens would have to pay as much as 68 percent of their health care coverage, up from 25 percent today, <a href="http://www.cbsnews.com/video/watch/?id=7417870n" target="_hplink">CBS News reports.</a>

  • Cuts To Food Stamp Programs

    Ryan's proposed "Path to Prosperity" includes $134 billion in cuts to SNAP, according to analysis from the <a href="http://www.washingtonpost.com/business/economy/2012/04/02/gIQAjn0grS_graphic.html" target="_hplink">Center on Budget and Policy Priorities</a>.

  • Lower Tax Credit For Single Moms

    A single mother of two working full time at the minimum wage would have her Child Tax Credit cut by more than $1,500, assuming she made $14,500 a year, according to the <a href="http://mediamatters.org/research/2012/08/11/seven-things-the-media-needs-to-know-about-paul/189277" target="_hplink">Center on Budget and Policy Priorities</a>.

  • Less Money For Education

    Compared to the most recent White House budget proposal, Ryan's budget spends 33 percent less on education, training, employment and social services, <a href="http://www.washingtonpost.com/blogs/ezra-klein/wp/2012/08/12/what-paul-ryans-budget-actually-cuts-and-by-how-much/" target="_hplink">the <em>Washington Post</em> reports</a>.

  • Poor Weather Forecasts

    Ryan's proposed cuts to environment and natural resource programs could result in weather forecasts being only half as accurate, according to Third Way's budget expert, David Kendall. "For many people planning a weekend outdoors, they may have to wait until Thursday for a forecast as accurate as one they now get on Monday," <a href="http://www.washingtonpost.com/blogs/ezra-klein/wp/2012/08/12/what-paul-ryans-budget-actually-cuts-and-by-how-much/" target="_hplink">he's quoted as saying in the <em>Washington Post</em></a>.

  • No Raises For Government Workers

    The current government worker pay freeze would be extended under the "Path to Prosperity," meaning public-sector employees wouldn't get a raise until at least 2015, <a href="http://www.washingtonpost.com/blogs/federal-eye/post/paul-ryans-budget-plan-hits-federal-workers/2012/08/11/8953b832-e3a3-11e1-98e7-89d659f9c106_blog.html" target="_hplink">the <em>Washington Post</em> reports</a>.