Blogger API V3 with Browser based OAuth2

I am trying to setup OAuth2 for the Blogger V3 APIs. But, I am stuck at the 
last step.

The current implementation successfully generates an access key, but the 
access key doesn't work when I try to make a Blogger API call.

The error, looks like the access key I get is somehow invalid.

Authorization: Bearer ya29.AHES6ZR_IEjiJ_BTRCpmr-CJ7jXNuXXXXXXX
The OAUth scope that I have used is:

https://www.googleapis.com/auth/blogger 
I tried generating an access token through the OAuth Playground, but the 
access token from there also doesn't work. It gives the same error.

{
    "error": {
        "errors": [
            {
                "domain": "global",
                "reason": "authError",
                "message": "Invalid Credentials",
                "locationType": "header",
                "location": "Authorization"
            }
        ],
        "code": 401,
        "message": "Invalid Credentials"
    }
}
I used this tool to check the status of the access token I possess, and 
this atleast says that the token is valid.

https://www.googleapis.com/oauth2/v1/tokeninfo?access_token=[access_token]
{
    "issued_to": "147XXXXX338.apps.googleusercontent.com",
    "audience": "147XXXXXXX338.apps.googleusercontent.com",
    "user_id": "11XXXXXX1949",
    "scope": "https://www.googleapis.com/auth/blogger 
https://www.googleapis.com/auth/userinfo.email 
https://picasaweb.google.com/data/ https://www.googleapis.com/auth/plus.me",
    "expires_in": 2372,
    "email": "[email protected]",
    "verified_email": true,
    "access_type": "offline"
}

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