The state orders all businesses, except those selling necessities, to be closed on Tisha B'av. It is prohibited for cafes, gyms, nightclubs, and movie theaters to be open on Tisha B'av. The only other day of the year that Israel enforces such a ban is Yom Kippur, the holiest day of the Jewish year.
Religious Jews observe the day by fasting. Secular Jews will commemorate the day in a more low key manner, but they will note it. There is no Israeli that does not feel the pull of the Temple and Wall. I have pictures of my great aunt Fela, who was an avowed secularist, rushing to visit the wall in the days after Israel recaptured it during the 1967 Six Day War.
Israelis were buzzing with excitement upon the arrival of Obama in 2008. The Jewish press is already noting that Romney's arrival has received a ho hum reaction. Romney came to Israel to shore up his Jewish vote, but by arriving on a somber Jewish holiday he risks offending his mostly likely Jewish constituency-religious Jews. He has already been forced to change a fundraiser to the next day.
I really hope that Romney does not exacerbate his mistake by desecrating the holiday with the staging of a photo opportunity at the Wall on its most somber day. Jews should be allowed to pray at the Wall on this special day without the distraction and interruption that a Romney visit and the accompanying media will bring.