In the aftermath of the highly anticipated debate between President Joe Biden and former President Donald Trump, initial post-debate polls indicate that Trump may be gaining ground in the race for the presidency. While it is still early in the election season, these polls have raised concerns about Biden's mental and physical fitness to serve as president for another term.

According to the national polling average by 538, Trump now leads Biden by 1.4 percentage points, compared to a tied race just a few months ago. Several polls conducted immediately after the debate also showed Trump in a stronger position compared to previous surveys. Data for Progress found Trump ahead by 48 percent to Biden's 45 percent in their latest national survey, a shift from an earlier poll in May where Biden had a slight lead.

Suffolk University/USA Today's post-debate survey revealed Trump leading 41 percent to Biden's 38 percent, indicating a change from a tied race in late April. Canadian pollster Leger, in collaboration with the conservative New York Post, experienced an even more significant shift, with Trump going from a 2-point deficit just before the debate to a 7-point lead afterward.

However, not all post-debate polls showed a boost for Trump. Some pollsters, like SurveyUSA, did not have a recent comparison point, while Morning Consult's national polling showed the race essentially unchanged with both candidates tied at 44 percent. CNN/SSRS's latest poll had Trump leading by 6 points, the same margin as their previous survey in late April.

Despite the mixed results, post-debate surveys revealed negative data points for Biden's standing, even within his own party. The 538/Ipsos survey found a drop in the percentage of likely voters rating Biden's mental fitness as excellent or good, with a significant decrease among Democrats. Similarly, a YouGov/CBS News poll showed that only 27 percent of registered voters believed Biden had the mental and cognitive health to serve as president, compared to 50 percent who believed Trump did. There have been discussions in the media and among Democrats about the possibility of Biden dropping out of the race, although this remains uncertain.

While alternative candidates were considered in some post-debate surveys, they polled similarly to Biden. Vice President Kamala Harris, seen as the most likely replacement choice, had identical poll numbers to Biden in several surveys. However, there were variations in CNN/SSRS's findings, with Harris trailing Trump by 2 points compared to Biden's 6-point deficit.

538's presidential election forecast has not experienced significant changes due to the post-debate polls, maintaining a coin-flip race between Biden and Trump. It is important to note that the forecast is relatively conservative at this stage, and small and inconsistent shifts in national polls are not expected to cause drastic swings. However, if state-level polls show more movement toward Trump in the coming days, the forecast could start to shift in his favor.

Despite Biden's struggles in the debate, any dramatic polling movement in the next couple of weeks would be surprising, given the highly polarized nature of the electorate. Voters who are already leaning toward one of the major-party contenders are unlikely to switch allegiances. Nevertheless, even small shifts in voters' preferences could have a significant impact on the final outcome, especially considering the competitive nature of recent presidential elections.

As we move forward, it will be crucial to closely monitor state-level polling, as the outcome of the elections is ultimately decided in the Electoral College. A slight shift towards Trump in certain parts of the electorate, compared to four years ago, could potentially pave the way for a Republican return to the White House.