ALL CAMPAIGNS, including trump's, *RELY* on polling information year round. It helps any campaign identify key areas for improvement in their messaging, ads, and narratives as they move forward. Much like football teams making adjustments at halftime based on what they learned in the first half, this important information helps campaigns craft a better second half and hopefully effect positive change in their favor.
UPDATE, JULY 3:
States which trump won in 2016 that are 'swing states' for 2020.
Shows the mean average result of MULTIPLE-polling data, with electoral votes in parentheses.
Joe Biden needs only to win any 3 of these 9 swing states,
*OR* win just two if one of them is Florida, and the DEMS have the WH again!
*Note that there are NO Democrat states in serious play,
while the Republicans are defending 9 and must win at least 7 despite these polls.
TIED again, Texas (38) ... was trump +1
+1 Biden, OHIO (18) ... down from +2
+2 Biden, Georgia (16) ... was TIED !
+5 Biden, Arizona (11) ... up from +4
+5 Biden, N.Carolina (15) ... up from +4
+6 Biden, FLORIDA (29) ... up from +5
+7 Biden, Wisconsin (10)
+7 Biden, Michigan (16)
+7 Biden, Pennsylvania (20)
Source: https://www.270towin.com/