Evidence from the 2020 campaign indicates that Biden’s relatively low‑visibility, home‑based (“basement”) strategy remained effective and that he sustained a clear lead over Trump through Election Day.

• Strategy and style of campaign: Contemporary coverage described Biden’s low‑key, largely home‑centered campaign as an intentional contrast with Trump; the Guardian noted in June 2020 that, despite Republican mockery of him “hiding out in his basement,” Biden’s low‑key approach to campaigning is paying off, with strong national and battleground-state leads. (theguardian.com) PolitiFact separately documented that the Trump campaign kept attacking Biden for supposedly staying in his basement, confirming that this was widely seen as his signature strategy even into the fall. (politifact.com) Washington Post reporting from July 2020 shows Biden explicitly defending frequent appearances from his house and emphasizing virtual outreach, reinforcing that this cautious, low‑visibility style persisted deep into the campaign. (washingtonpost.com)

• Polling from prediction date (July 2020) to Election Day: National polling averages in early June and July 2020 already showed Biden with a sizable lead, roughly 7–8 points over Trump. (cnbc.com) Through late September and mid‑October, CNBC and other aggregators reported that Biden continued to hold a stable national advantage of about 7–10 points, with RealClearPolitics and FiveThirtyEight showing him consistently ahead. (cnbc.com) On the eve of the election (November 2, 2020), Biden still held a strong national lead—around 6.5–8.4 points in major polling averages—despite some tightening in key swing states. (cnbc.com) At no point after July did Trump surpass Biden in the major national polling aggregates; Biden’s lead persisted, even if its exact size fluctuated.

• Election outcome: In the final certified results, Biden won the national popular vote 51.3% to 46.9%, a margin of about 4.5 percentage points, and secured 306 electoral votes to Trump’s 232. (pewresearch.org) This confirms that, in electoral terms, his campaign approach did not undermine his advantage; he converted his sustained polling lead into both a popular‑vote and Electoral College victory.

• Comparing to the prediction’s wording: The prediction was that continuing a low‑visibility, basement‑style strategy would keep working, such that Biden would sustain or increase his lead over Trump “up through the election.” The record shows:

  • Biden’s strategy remained comparatively low‑key and home‑based through 2020, especially relative to Trump’s rally‑heavy schedule. (theguardian.com)
  • Biden maintained a clear national lead from July 2020 through Election Day; while the margin narrowed somewhat in the final days, it never disappeared, and Trump never overtook him in the major national polling averages. (cnbc.com)
  • Biden ultimately won by a solid popular‑vote margin and a comfortable Electoral College count. (pewresearch.org)

Because the core claim—that sticking with this low‑visibility approach would remain effective at keeping Biden ahead of Trump through the election—matches both the polling trajectory and the final result (even if the lead slightly narrowed rather than strictly increased), the prediction is best judged as right overall.