From a Refugee Crisis to a European crisis: does the influx of asylum seekers affect attitudes towards further integration of the European Union?

The attitude towards further integration of the EU has decreased over the past decade. Meanwhile, Europe has experienced a Refugee Crisis. I have been looking into the effect of the influx of asylum seekers per thousand residents on attitudes of European citizens towards further integration of the EU. Estimating an ordered probit model, controlling for country and year fixed effects, country-specific factors, individual characteristics and the influx of immigrants per thousand residents, I found a significant, positive effect. However, this effect is rather small. Moreover, there are some concerns about omitted variables and reversed causality causing bias regarding this estimation. Therefore, I have also estimated an instrumental regression, including year and country fixed effects, controlling for the influx of immigrants per thousand residents. The increase of influx of one asylum seeker per thousand residents, significantly decreases the attitude towards European integration with 0,2 on a scale from 0 to 10. One can conclude there is small but significant negative effect.