Science is a process that can be used to come closer to the truth than mere cheerleading for one's candidate. I am going to demonstrate where both Biden and Trump claims are opinion and not truth! Science says that I can only use gathered, observed, material data to come to a truthful conclusion. So let us see where they have any material evidence.
Trump claims that if he did not act to effect Covid with his policies, Covid would have killed two million plus individuals. Where is the hard material, evidence data? Since Trump instituted active policies that affected how Covid performed, we no longer have unaffected evidence to prove the two million death figure. But you say some scientist has run a model, or used history to get an educated GUESS! It is a subjective guess and not objective reality with out actual evidence due to no interference from Trump's policies. From the scientists view the two million plus death is possibly an educated guess. But in reality it is subjective, not objective truth backed by obtainable, observable evidence.
The same is true for Biden in his claims that If he had been president, his policies would have prevented the two hundred thousand plus deaths that we do have some hard evidence for. Since he did not implement his policies, we have no hard evidence from his policies,
Therefore, his assertions that he would do better than Trump are scientifically invalid! Where you do not have the actual observable evidence (and since he did not institute his policies), he is making a claim that he cannot back up with indisputable hard facts! Biden is guessing! As usual, so many political candidates claims have much rhetoric with no objective facts to back up those claims. (By the way, this is where both candidates start lining up EXPERTS on their side.) What is my observation of what man does in this situation? Man makes a leap of belief that his candidate's claimed truth is correct. However, just remember that your subjective belief is not verifiable truth and you could be wrong!!