Nicola Lamb: Numbers tell worrying story for Trump

Republican presidential contender Donald Trump is good at lighting headline fires that keep the TV lenses on him and the office talk about him.

But behind the noise and emotion, the data on this US election increasingly shows Trump's campaign teetering behind the scenes. It is starting to resemble 2008, when John McCain fought the daily battle to dominate the news cycle, while Barack Obama stuck to a steady strategy.

Trump had a good polling period leading up to the two party conventions in July. But in the past fortnight the gap has widened in Clinton's favour. The major caveats are 1) we need more information on this trend 2) there's still a long way to go 3) polls show that many voters feel the country is on the wrong track and 4) the debates and other possible surprises are still ahead.

But nearly two weeks after the Democratic Convention, the party's nominee, Hillary Clinton, is still more than holding onto an important bounce in the polls.

At a time - 12 days after the convention ended and when her poll bounce could be expected to decline - she is in a better position than last weekend.

On Sunday, RealClear Politics.com gave Clinton an average national poll lead over Trump of 6.9. She had a 16.7 higher favourable rating than Trump and the betting odds favoured her by 76 to 24.

Days later, only the odds have remained static. Her national poll lead is up to 7.9 and her higher favourable rating, according to RCP, has nudged to 16.9.

Nate Cohn of the New York Times tweeted this week: "Clinton favourability bounce has faded a bit, per Gallup. But Trump isn't recovering - he's slipped post-DNC."

In this week's national polls, Clinton leads Trump by 7 (Economist/YouGov); by 10 (NBC/SurveyMonkey); and by 13 (Monmouth).

Clinton's poll averages in battleground or swing states - the close contests that essentially decide the race for the White House - are quietly improving.

She was trending up last night in RCP's poll averages for Pennsylvania (+9.2), Ohio (+2.6), and Iowa (+0.7).

The overall picture is she leads in all RCP's battleground states except for Missouri (Trump +6.3) and Arizona (Trump +0.3).

And there are healthy leads in key Electoral College states: Pennsylvania, Virginia (+7), New Hampshire (+7), Michigan (+6.6), Wisconsin (+5.6), Colorado (+9.5).

Clinton is essentially doing well in several of the Rust Belt states which voted for Obama that the Trump campaign sees as crucial to its success with his core constituency of blue collar white males.

The battleground states traditionally considered the most important are Pennsylvania, Ohio and Florida. The latter two are still very tight but Pennsylvania is becoming increasingly secure for Clinton.

Academic Daniel Nichanian, who tweets as @Taniel, notes that Clinton has led Pennsylvania's last four polls by double-digits. "NBC/Marist just released 4th consecutive poll with HRC leading Pennsylvania by 10-11%. One of most important states uncompetitive for now."

Cohn tweeted: "All the polls agree on this: Clinton has about a 10 point lead in Pennsylvania, and Trump's path is very difficult without it."

Election statisticians and reporters on Twitter have recently been comparing Trump's polling performance to that of Republican nominee Mitt Romney against Obama in 2012.

Benjy Sarlin, who covers the Republican race for NBC, tweeted that at this stage of the 2012 contest, "Clinton is about where Obama was. Trump is 10 behind Romney".

About the traditionally Republican state of Kansas, where Trump is leading by 5 per cent in a new poll, Cohn tweets: "In the @FiveThirtyEight polls-only model, Clinton has a better chance of winning Kansas than Trump has of winning the presidency". Taniel tweets that "Trump leads by 5% in Kansas, says SUSA (44-39), down from an 11% lead in July (47-36). Romney carried the state by 21%."

What do the trends suggest overall?

Nate Silver of fivethirtyeight.com explains that Clinton has "gone from having roughly a 3 or 4 percentage point lead over Donald Trump in national polls in early July to more like an 8-point lead now. Therefore, we'd expect her to gain perhaps 4 or 5 points in polls of Pennsylvania, Florida, Ohio and other swing states ... [today] we finally got a bunch of state polls to test the theory ... Clinton gained an average of 4 percentage points across the six surveys. The clearest trend toward Clinton is in Pennsylvania, which is now part of her path of least resistance to 270 electoral votes."

Talkingpointsmemo.com predicts - as of now - a landslide win to Clinton of 342 EC votes to Trump's 164. A total of 270 are needed to win the presidency.

Josh Marshall, TPM's editor, tweeted: "This bears repeating: States in which Clinton is beating Trump by AT LEAST 10 POINTS account for 253 electoral votes".

Silver is more cautious: "Clinton is polling really well right now, and if you held an election today, she'd probably win in a landslide, possibly including states such as Georgia and Arizona along with most or all of the traditional swing states. Still, Clinton doesn't quite have a firewall of 270 electoral votes. If Trump makes a big comeback, her Electoral College position is decent but not great."