It depends on the slogan. A purely descriptive or promotional slogan ("Quality You Can Trust," "Always Fresh") will weaken the overall distinctiveness of the logo mark and may trigger a refusal or an objection from the examiner. In that case, removing it from the logo application and considering whether it merits a separate wordmark application on its own grounds is the cleaner approach.
A slogan that is inventive, unexpected, or has acquired strong consumer recognition can actually strengthen the mark. The question is whether the slogan, as a text element within the logo, adds to or detracts from the overall distinctiveness of the combined mark.
If you are unsure whether your slogan helps or hurts the application, assess it as a standalone wordmark first. If it would be refused as a wordmark on distinctiveness grounds, including it in the logo is unlikely to help.