If a runner from 2nd base running towards 3rd base realise he may not make it in time, is he allowed to run back to 2nd base?

In baseball, a runner is allowed to return to a previously occupied base if they determine that they cannot safely reach the next base (in this case, third base). However, there are specific rules governing this situation:

1. Tag Up: If the runner has not yet been put out (tagged or forced out) and has not passed third base, they may return to second base without any issues.

2. Defense Actions: While the runner is attempting to return to second base, the defensive team can tag them out if they successfully reach second base with the ball before the runner gets there.

3. Force Play: If the runner has already passed second base and is attempting to return, they can be put out with a force play if the defensive team touches the base before the runner returns.

In summary, the runner is allowed to run back to second base, but they must be vigilant about the defensive players' actions that may lead to them being tagged out during their return.