My spreadsheet since May for SPX with data from the WSJ.
Date / SPX 12 month forward earnings estimate / 12 month price earnings ratio
5/06 116.95 17.59
5/13 116.15 17.62
5/20 117.21 17.51
5/27 118.26 17.75
6/03 117.86 17.81
So the earnings number has fluctuated somewhat - down a bit, up decently, down a bit but the p/e has remained in a tight range from 17.50 to near 18 yet not above on a weekly basis. Right now 18x forward earnings is 2121. Obviously this will also continue to fluctuate somewhat depending on the earnings estimates but this number is still near enough to the all time high (only 13 points) for a test.
The Citigroup Economic Surprise Index looked to be perking up until Friday but still below the zero line.
We may see differently as time unfolds but with FOMC and election uncertainty, I don't believe we will see substantially above 18x forward earnings. And until the economic index moves decently into positive territory, ie, data is coming in better than expected, the case is weaker for convincing new all time highs across the board on the USA main indexes.
Sum: both should be limiting upside, yet could be room to test the 2015 highs. Not sure how much downward pressure.