Donald Trump flatlined through his four years after Day 20, with his job approval rating never cracking the 50 percent mark. Trump “peaked” at 45 percent, which is where Biden is now; but Trump never went below 37 percent. So that’s what floors look like in the current environment.
As for the best-case scenario for Biden: Obama’s first term approval number after one year bounced around between 43 percent and 54 percent.
Events can influence job approval numbers. Both Bush first terms occurred during times of war, so their job approval spikes should be viewed within that context. And Carter’s ill-fated effort to rescue the Iranian hostages caused a spike in his job approval, which fell sharply as the crisis continued.
But absent a black swan event, the path back might be a reevaluation of how Biden approaches his job. Clinton’s and Reagan’s slides occurred until both lost control of one or both chambers of Congress, prompting both to rethink their approach to governing. Both reclaimed much of their post-one-year slides in the runup to reelection.