Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| District | Incumbent | Party | First elected | Results |
| --- | --- | --- | --- | --- |
| Colorado 1 | Diana DeGette | Democratic | 1996.0 | Re-elected |
| Colorado 2 | Mark Udall | Democratic | 1998.0 | Re-elected |
| Colorado 3 | John Salazar | Democratic | 2004.0 | Re-elected |
| Colorado 4 | Marilyn Musgrave | Republican | 2002.0 | Re-elected |
| Colorado 5 | Joel Hefley | Republican | 1986.0 | Retired Republican hold |
| Colorado 6 | Tom Tancredo | Republican | 1998.0 | Re-elected |
| Colorado 7 | Bob Beauprez | Republican | 2002.0 | Retired to run for Governor Democratic gain |
Question:
What district is the incumbent Republican and the incumbent retired to run for governor democratic gain?
Answer:
Colorado 7