Maybe an example (any would do) to illustrate this outrageous assertion would be appropriate.

"I totally dismiss" the "outrageous assertion," Mr. Bush said, his jaw clenched and his face turning red.

But he is given to making outrageous assertions in speeches.

Some South African Dutch reformed theologians claim Scriptural support for the outrageous assertion that blacks are an inferior race of people.

Indeed "The Eagle's Shadow" is filled with dubious generalizations and outrageous assertions.

But in my own life and work, I am the unwelcome contrary; I am the refutation of such preposterous, indeed, outrageous assertions.

The Peers plainly granted no credence whatever to the lady's outrageous assertion.

This is an outrageous assertion, even for the most egomaniacal of Juilliard freshmen.

Mrs Lagarde must take back her outrageous assertions: jealousy should not be a factor in the politics of European neighbours.

You should publicly withdraw the Czech Presidency's outrageous assertion that whoever does not accept the Treaty of Lisbon should leave the Union.