The Republicans’ man-centric campaign might cost them the election, according to a former advisor to President Clinton, who says that historical trends of women leaving the GOP, combined with their higher turnout on Election Day, could power a Democratic victory. 

Doug Sosnik is a veteran political strategist who served as a chief advisor to Mr. Clinton in his second term. Since serving under the president, he’s become known for the shrewd political analysis he’s given Democrats, even if his analysis has sometimes been a bitter pill for Democrats to swallow.

This past spring, Mr. Sosnik was ringing the alarm bells about President Biden’s narrowing path to re-election. In mid-July, he made the case that that path had “all but vanished.” 

Now, the veteran political strategist is making the case that Vice President Harris can win, describing how the GOP’s man-focused strategy, demonstrated by the choice of Senator Vance as President Trump’s running mate and the Republican National Convention’s “Trumpomania” speaker list, might cost them the election.

The flip side of this equation is that women are flocking to the Democratic Party and, as Mr. Sosnik sees it, this could shake out better for the Democrats than the Republicans.

In his memo, Mr. Sosnik notes that women already tend to vote Democratic — they supported Mr. Biden more than Trump, 55 percent to 44 percent, in 2020 — and that the gender gap in voting “is likely to widen and could determine the outcome of the upcoming election.”

The reasons he lays out are multifaceted. First, women are simply more reliable voters than men and they have been for decades. In 2020, 68.4 percent of women eligible to vote turned out compared to 65 percent of men.

The gender gap is even more pronounced in swing states like Michigan, Wisconsin, Pennsylvania, Georgia, Nevada, and North Carolina.

Secondly, this will be the first national election since Roe v. Wade was overturned, and women have increasingly identified as in favor of abortion rights.

In 2020, a similar proportion of women identified as generally “pro-life” and “pro-choice,” according to Gallup polling. Now, 63 percent of women identify as “pro-choice” compared to 33 percent who identify as “pro-life.”

Among men, the difference is much smaller, with 49 percent self-identifying as “pro-life” compared to 45 percent who say they’re “pro-choice.”

Certain groups of women have moved toward Democrats more than women as a whole, such as college-educated women, who favored Mr. Biden by 9 points in 2020. For context, Senator Clinton won this group by 7 points in 2016 and Senator Romney won this group by 6 points in 2012.

Young women also self-identify as “liberal” far more than men. Among women younger than 30, 40 percent use this label compared to 25 percent of men.

“If these factors aren’t enough, the style and substance of Trump’s campaign, with his intemperate remarks about Harris’s sex and race, and the selection of his running mate, JD Vance, who has a long history of making disparaging remarks about women, will further alienate women voters,” Mr. Sosnik writes.

He also points out that so far Ms. Harris “has not lost a single news cycle since she announced that she was running for president,” and that Democratic enthusiasm for their candidate has been eclipsing Republican enthusiasm, with 85 percent of Democrats and 71 percent of Republicans saying they are enthusiastic about their party’s nominee, according to a recent Monmouth poll.

This enthusiasm, as Mr. Sosnik sees it, is likely to continue through the Democratic National Convention and up to the presidential debate scheduled for September 10, which comes less than a week before early voting starts in Pennsylvania.