Hall, who received the endorsement of Prime Minister Rishi Sunak last week, has been accused of failing to "fairly represent" the diversity of the capital by liking and retweeting posts that are seen as racist and offensive by many Londoners.
Among her social media activity, Hall liked a tweet that praised former Conservative minister Enoch Powell, who gave a notorious speech in the 1960s linking immigration to "rivers of blood".
She also replied to a tweet by right-wing commentator Katie Hopkins that called London mayor Sadiq Khan "our nipple-height mayor of Londonistan" with "Thank you Katie!".
Hall also made comments that suggested Khan's "divisive attitude" left Jewish residents frightened and engaged in "Islamophobic tropes" about him, according to The Guardian.
A poll commissioned by the anti-racism group Hope Not Hate found that 60 percent of respondents think Hall should be suspended from the Conservative party and investigated, while 64 percent said they view a mayoral candidate who "likes" Islamophobic tweets as racist.
Georgie Laming, director of campaigns at Hope Not Hate, said: "It's clear that Londoners think that Hall is not fit to represent London. The Conservative party must suspend Susan Hall immediately and she must be removed as a candidate."
A spokesperson for Hall said: "Susan is proud to celebrate London's diverse communities and as mayor she will fix the bread-and-butter issues that people care about - making our streets safer and putting money back in your pocket. Susan regularly engages with people on Twitter without endorsing their views and wholly condemns any racism or Islamophobia on the platform."
Source: Agencies