Silicon Valley is working behind the scenes to secure senior roles for tech allies in lesser-known but still vital parts of president-elect Joe Biden's administration, even as the pushback against Big Tech from progressive groups and regulators grows.

The Biden transition team has already stacked its agency review teams with more tech executives than tech critics. It has also added to its staff several officials from Big Tech companies, which emerged as top donors to the campaign.

Now, executives and employees at tech companies such as Alphabet Inc.-owned Google, Amazon.com Inc., Facebook Inc., Microsoft Corp. are pushing to place candidates in senior roles at government agencies, according to four sources with knowledge of the matter.